I still haven't figured out how to take screenshots in this game, so these are just generic images (all from Softpedia). Sorry. Anyway, I told you of my initial impressions last week, and I haven't changed my mind. This game is still fun, if not exactly what I'd hoped.
Your soldiers in XCOM: Enemy Unknown are class-based. Unlike the original X-COM, you can't equip your soldiers any way you want. They're limited by class - and, oddly enough, you can't even pick which class. You can, however, pick which soldiers you take on assignment.
In general, I'd say it's a very good idea to take at least one of each class to every fight. They're all useful, even critical at times. You seldom know the terrain ahead of time, or what enemies you'll encounter, or which abilities you'll really need the most. Still, I have my favorites...
Before I start, note that you can't see class abilities before you get a character of that particular class promoted to the appropriate rank. I won't be too specific here, but if you'd rather find out all of this for yourself, stop reading now. Clear?
In most cases, you can choose one of two abilities for a soldier at each promotion. But I won't talk about all the choices. I won't even specify which I took. I will say that, in most cases, it hasn't been a difficult decision. I've never really been forced to choose between two great abilities (sometimes between two mediocre ones, though).
Anyway, my favorite class is the sniper, I think. Colonel Karin Jensen, from Denmark, is just a killing machine. Snipers can't shoot their rifle after moving, so you have to be very careful with them. (I almost lost her in this battle.) They're not good in close combat, and you really don't want to lead with them.
But if you can set them up with a clear view of the battlefield, preferably somewhere at high elevation, they're incredibly deadly. They can shoot very long distances, particularly if another squad member can see the enemy, and they're extremely accurate. They can one-shot some especially dangerous foes, and they just get more and more deadly with higher rank.
In tough fights, I frequently take two high-level snipers with me. But you want to keep them in the back and move them as little as possible. Ordinarily, you don't want to move them at all until everyone else has already moved and set up on overwatch, clearing the way.
And if I have two snipers, I usually keep one on overwatch as I move the other (or as the other reloads). No one is as deadly as a sniper in a good position. You can tell how valuable a sniper is by how much you miss her when she's not available!
My second favorite is the assault class. Yvonne Torres, from Argentina, is only a major, and she has just half the kills of my two colonels. But part of that is because she's always in the lead (unless I've got a rookie to spare), so she spends a lot of time in the hospital. :)
The neat thing about assault soldiers is that they can "run and gun." In other words, unlike other classes, they can sometimes choose to move twice and still shoot (or stay on overwatch). For your lead soldier, that's really valuable.
Sometimes, there's just no cover available close enough, so one soldier has to run ahead. Any other soldier would be helpless at that point, if she encountered an alien (or even if aliens found her, on their turn). This ability can also be useful to flank an alien. Assault soldiers can run around to the side and then shoot, getting a much better angle of fire (and a much better chance to hit).
However, most often, I just keep this ability in reserve while scouting ahead. I can move Major Torres normally, and then, if it turns out to be necessary, choose her "run and gun" ability on her second move. That means she'll be able to run back again, or run elsewhere to cover, if she encounters too many aliens, and still defend herself, too.
Assault soldiers also get the ability to avoid reaction shots, which has probably saved her life any number of times. And she can even get a free reaction shot on enemies who get too close. She hasn't actually used that ability, not yet, but it's really a comfort to have it when Chryssalids are around! (And in terror attacks, her "run and gun" can help save civilians from them, though this is still very, very risky for her.)
As with snipers, on tough fights, I frequently take two assault soldiers, too (often we need to advance on two fronts). They don't get as many kills as other classes, but that's partly because I let my snipers take those shots, so my lead soldier still has some capacity for defense (and partly, as I say, because lead soldiers frequently end up in the hospital).
Next is the class of my longest-serving soldier, Colonel Jose Luis Soto, a heavy, also from Argentina. He was that sole survivor from the tutorial (there's no way you can save the other three soldiers in the tutorial battle), and he's been with me ever since.
Even at very low level, a heavy can fire a rocket. Now, I don't often do that, because it destroys alien equipment, but if you get swarmed by aliens, a well-placed rocket can save lives. Colonel Soto has more kills than anyone but my top sniper, but some of those were group kills, from rocket attacks.
Still, he does very well against single opponents, too. His main weapon does more damage than most, and he can suppress enemies and get a free reaction shot when they move. (The downside is that he burns through ammunition very quickly.) His is also the only class which can shoot first and then move. So, sometimes, he'll take a risky shot just because I know he can run back to safety afterwards.
Still, Colonel Soto can't fire his rocket if he's moved first. So I rarely put him in the lead, just in case it turns out that I really need that rocket. He tends to be one of the last people I'll move in a turn (except for the snipers). And I guess that might also be why he gets so many kills.
Finally, there's the support class. Major Konstantinos Mikos, from Greece, is my top guy there. Major Mikos is my healer, but he also has some pretty good suppression abilities (like the heavy). He has fewer kills than the rest of these soldiers, because I tend to keep him in the back, in the middle, close to other soldiers, where he can rush to heal anyone who gets injured.
Keep in mind that I don't know what skill colonels in the assault and support classes get, since I don't have a colonel in those classes yet. So far, the support class might be my least favorite, but I wouldn't fight a battle without at least one. You need his skills.
To close, I suppose I should mention rookies. Except for really tough fights (we're often told how difficult an assignment will be), I frequently take a rookie along - or a squaddie, if I don't have a rookie - for the experience.
Rookies are expendable, so I give them the worst equipment (the entire Earth can't afford to outfit six guys with the good stuff, you know) and usually tell them to take the lead. In fact, the only soldier I've ever lost was a rookie, shot in the head by a Muton, even as he sheltered behind pretty good cover. That was a shame, but it was better than losing someone experienced!
Now, though, battles are getting so tough that it's difficult to bring a rookie. After all, I can only take six guys, and we're always up against superior numbers and superior firepower. But I've still got to train my young soldiers, in case I lose my best.