SWTOR is going to rejigger the whole concept of classes and combat styles with the next expansion in December, but one thing that's remained the same and will remain so is the fact that it has 8 storylines (generally referred to as classes) for the base game, 4 Imperial and 4 Republic. I've completed 5 so far and intend to go for them all. For the 6th one, I picked the Trooper. Behold, Kaltamze the Mirialan Vanguard! Screencap album.

The Trooper is so far extremely underrated. The whole "Republic Trooper, special forces" thing is a neat explanation for why the fuck you're doing anything and why you care, and the prologue + chapter 1 plotline is extremely good.
You see, you've just been made a member of the elite special forces squad known as Havoc Squad, deployed on Ord Mantell. Your squadmates, Wraith, Fuse, Needles, Gearbox, and Tavus, send you on a few missions and compliment your skillz.

Havoc Squad gets the job done.
Then your squad defects to the Empire.
Turns out that the reason the Separatists on Ord Mantell were always ahead of you was that your comrades were feeding them intel! That bomb that could level hte entire island? The guys probably gave it to them.
(Why are there Separatists on Ord Mantell? Well, the movement has nothing to do with the prequels-era Separatists, but the game devs wanted to give Trooper players some of that Clone Trooper je ne sais quoi, ergo, the starter area's enemies are Separatists. Later you go against the Sith Empire.)

Just wanted to highlight the chin/throat scar. And the same hairstyle as General Garza.
The prologue and chapter 1 are about bringing the traitors in. There's some intriguing background hints given about why they defected – they felt betrayed by the Senate and General Garza, their superior, for being abandoned without support or extraction on a mission gone wrong – and then there is a great amount of ... well, the moral conflicts aren't "nice person vs selfish jerk", they're about for the people vs for the military. Are you a rule-follower or do you do what you think is best? In a way, it's like for the Imperial Agent – following orders vs independence – except that following orders to the letter is LS for the Agent but DS for the Trooper.
Kaltamze, so far, is mostly LS in that she does, actually, believe in civilian oversight of the military and will share intel if it is necessary. She doesn't take every LS decision, though, and her attitude is "For the Republic!" rather than "For General Garza!"
The planet plots are pretty straightforward, in that they're all "dismantle traitor's plot, get traitor". Coruscant starts with the prior Havoc Squad's retired mentor, as it's still the prologue and thus can't hit the big notes yet; Kaltamze convinced him to help bring Havoc back rather than killing him. Of course, because video game, it made no difference whatsoever, but: technically good for intel, I guess.
Old Havoc's members have scattered to a bunch of planets. Needles, the requisite mad scientist, has gone to Taris to weaponize the Rakghoul plague (basically zombies) using random passersby as his test subjects. The planet plot itself was kind of shrug; the main attraction was getting companion #2, Elara Dorne. Nar Shaddaa was similar – Traitors Havoc has kidnapped an experimental robot and forced him to fight for them, and then you free him and get him as companion #3, M1-4X.

The planet plotlines get interesting with Tatooine. See, Fuse is Traitors Havoc's bombmaker, and he and his Imps are testing the bombs on out-of-the-way Tatooine. Except that the Imps are testing the bombs on civilians. Fuse has regrets, which makes for a more interesting planet than Taris or Nar Shaddaa. Then at the end, he gets to die heroically as we only have time to either stop the Imp base self-destruct or stop the evacuating Imp with the bomb plans (leaving Fuse to die in the brig). Kaltamze the right thing, which is also what Fuse wanted. Sorry Fuse. You were an idiot, but a help at the end.

I'm not that much one for Space Barbie but I am happy with how Kaltamze now looks!
Alderaan involves a Thul noble telling you he'll tell you where the final non-commander, Gearbox, is, as long as you extract his wife and daughter first. The rescue mission was nice, as the wife is all "oh noo, you're going to get us all killed!" while the daughter was, uh, very excited to be able to run around in a disguise. The actual showdown with Gearbox and his mecha was unexciting, even if the interaction he had with Elara was nice.

I love this shot.
The grand finale, of course, was Tavus, the CO of Traitors Havoc. We got to take over his entire Imperial ship, disabling the hyperdrive and massacring our way to the bridge! Then came the final bossfight, and after it, Tavus said he was very sorry and could give important intel. Kaltamze took the Light Side choice of handing him over to the interrogators for intel rather than executing him outright. Aric threw a hissyfit, but my take on Kaltamze is that she can look at the greater good – in this case, letting Tavus live so he can share all he's learned of the Imps. Besides, Garza will be on his case.

Holiday pics with the hyperdrive core.
I haven't started chapter 2 yet. Kaltamze's still enjoying her shore leave, perhaps in that Mantellian bar Aric recommended.
Now, the companions!
The starter companion is Aric Jorgan. One could, technically, call him a catboy, in that he's a Cathar, who are leonine humanoids. He's very grumpy for justified reasons, as he's first stuck in a career dead end on Ord Mantell, and then, because he was working with Traitors Havoc, he got demoted and became Kaltamze's underling after she got her promotion. He's someone where I think had I first met him via the Trooper story, I might've gotten a very different impression; as it is, I met him first in KOTFE, where he's still a grumpy lionman, but less bitter/annoying. He's the romance option for female Troopers, and Kaltamze's going for it.

Don't let the image fool you, Kaltamze and Aric are actually of a height.
Elara Dorne is a traitor – but from the Empire, not to. She's really into rules and regs, hasn't shed her accent, and is kinda prissy. I haven't spent as much time with her as with Aric, and her personality is less loud than M1-4X's, so I don't have much of an impression of her. Okay, I guess?

You can see half of Elara here. This is somehow the perfect representation of my opinion on her.
The third addition to New Havoc Squad is M1-4X, prototype droid who's part tank droid and part propaganda bot. He's hilarious. His persona is very OTT, but like, he's the comic relief. He's very good at it! His companion chat plotline is about assassinating Imperial figureheads, and the circumstances always end up being funny. I like him!

Side note: playing a good soldier who follows orders/isn't an asshole means I get, like, all of them approving for each of my "Sir, yes, sir"s to General Garza on the ship and whichever one I take with me gets some absurd amount of influence. It's like printing influence!

The Trooper is so far extremely underrated. The whole "Republic Trooper, special forces" thing is a neat explanation for why the fuck you're doing anything and why you care, and the prologue + chapter 1 plotline is extremely good.
You see, you've just been made a member of the elite special forces squad known as Havoc Squad, deployed on Ord Mantell. Your squadmates, Wraith, Fuse, Needles, Gearbox, and Tavus, send you on a few missions and compliment your skillz.

Havoc Squad gets the job done.
Then your squad defects to the Empire.
Turns out that the reason the Separatists on Ord Mantell were always ahead of you was that your comrades were feeding them intel! That bomb that could level hte entire island? The guys probably gave it to them.
(Why are there Separatists on Ord Mantell? Well, the movement has nothing to do with the prequels-era Separatists, but the game devs wanted to give Trooper players some of that Clone Trooper je ne sais quoi, ergo, the starter area's enemies are Separatists. Later you go against the Sith Empire.)

Just wanted to highlight the chin/throat scar. And the same hairstyle as General Garza.
The prologue and chapter 1 are about bringing the traitors in. There's some intriguing background hints given about why they defected – they felt betrayed by the Senate and General Garza, their superior, for being abandoned without support or extraction on a mission gone wrong – and then there is a great amount of ... well, the moral conflicts aren't "nice person vs selfish jerk", they're about for the people vs for the military. Are you a rule-follower or do you do what you think is best? In a way, it's like for the Imperial Agent – following orders vs independence – except that following orders to the letter is LS for the Agent but DS for the Trooper.
Kaltamze, so far, is mostly LS in that she does, actually, believe in civilian oversight of the military and will share intel if it is necessary. She doesn't take every LS decision, though, and her attitude is "For the Republic!" rather than "For General Garza!"
The planet plots are pretty straightforward, in that they're all "dismantle traitor's plot, get traitor". Coruscant starts with the prior Havoc Squad's retired mentor, as it's still the prologue and thus can't hit the big notes yet; Kaltamze convinced him to help bring Havoc back rather than killing him. Of course, because video game, it made no difference whatsoever, but: technically good for intel, I guess.
Old Havoc's members have scattered to a bunch of planets. Needles, the requisite mad scientist, has gone to Taris to weaponize the Rakghoul plague (basically zombies) using random passersby as his test subjects. The planet plot itself was kind of shrug; the main attraction was getting companion #2, Elara Dorne. Nar Shaddaa was similar – Traitors Havoc has kidnapped an experimental robot and forced him to fight for them, and then you free him and get him as companion #3, M1-4X.

The planet plotlines get interesting with Tatooine. See, Fuse is Traitors Havoc's bombmaker, and he and his Imps are testing the bombs on out-of-the-way Tatooine. Except that the Imps are testing the bombs on civilians. Fuse has regrets, which makes for a more interesting planet than Taris or Nar Shaddaa. Then at the end, he gets to die heroically as we only have time to either stop the Imp base self-destruct or stop the evacuating Imp with the bomb plans (leaving Fuse to die in the brig). Kaltamze the right thing, which is also what Fuse wanted. Sorry Fuse. You were an idiot, but a help at the end.

I'm not that much one for Space Barbie but I am happy with how Kaltamze now looks!
Alderaan involves a Thul noble telling you he'll tell you where the final non-commander, Gearbox, is, as long as you extract his wife and daughter first. The rescue mission was nice, as the wife is all "oh noo, you're going to get us all killed!" while the daughter was, uh, very excited to be able to run around in a disguise. The actual showdown with Gearbox and his mecha was unexciting, even if the interaction he had with Elara was nice.

I love this shot.
The grand finale, of course, was Tavus, the CO of Traitors Havoc. We got to take over his entire Imperial ship, disabling the hyperdrive and massacring our way to the bridge! Then came the final bossfight, and after it, Tavus said he was very sorry and could give important intel. Kaltamze took the Light Side choice of handing him over to the interrogators for intel rather than executing him outright. Aric threw a hissyfit, but my take on Kaltamze is that she can look at the greater good – in this case, letting Tavus live so he can share all he's learned of the Imps. Besides, Garza will be on his case.

Holiday pics with the hyperdrive core.
I haven't started chapter 2 yet. Kaltamze's still enjoying her shore leave, perhaps in that Mantellian bar Aric recommended.
Now, the companions!
The starter companion is Aric Jorgan. One could, technically, call him a catboy, in that he's a Cathar, who are leonine humanoids. He's very grumpy for justified reasons, as he's first stuck in a career dead end on Ord Mantell, and then, because he was working with Traitors Havoc, he got demoted and became Kaltamze's underling after she got her promotion. He's someone where I think had I first met him via the Trooper story, I might've gotten a very different impression; as it is, I met him first in KOTFE, where he's still a grumpy lionman, but less bitter/annoying. He's the romance option for female Troopers, and Kaltamze's going for it.

Don't let the image fool you, Kaltamze and Aric are actually of a height.
Elara Dorne is a traitor – but from the Empire, not to. She's really into rules and regs, hasn't shed her accent, and is kinda prissy. I haven't spent as much time with her as with Aric, and her personality is less loud than M1-4X's, so I don't have much of an impression of her. Okay, I guess?

You can see half of Elara here. This is somehow the perfect representation of my opinion on her.
The third addition to New Havoc Squad is M1-4X, prototype droid who's part tank droid and part propaganda bot. He's hilarious. His persona is very OTT, but like, he's the comic relief. He's very good at it! His companion chat plotline is about assassinating Imperial figureheads, and the circumstances always end up being funny. I like him!

Side note: playing a good soldier who follows orders/isn't an asshole means I get, like, all of them approving for each of my "Sir, yes, sir"s to General Garza on the ship and whichever one I take with me gets some absurd amount of influence. It's like printing influence!