I've gone with the assault class as of late. They have a boatload of health and their weapon is very accurate even at range and does a lot of damage.
Add on that spiffy underslung grenade launcher and you have a quick bunker clearer or use it against light vehicles.
My main problem with the game is that the heat seeking missiles are completely useless. By the time you lock onto something, it's already too far/close and you don't even have to make and dodging them requires little more than a slight turn. Then there's the flares that completely fool them.
I mean, if the missiles are going to be this bad in game, why not just give every anti tank man some?
I too like the assault-but the M16 is still shitty-and the Medic has WAAAY more versatility and all you sacrifice is the nade launcher, which is really very situationally specific as to its usefulness-I mean unless you are taking potshots at BMP's and have PLENTY of time to reload or can see groups of infantry to really make use of it, its inefficient and hard to aim. Anyways, the alt weapon for the assault does make it a lot more palatable.
I still think I will be sticking with 1. spec ops (w/g36c unlocked), 2. Medic (primarily with LE unlocked) and 3. Assault (w/alt weapon). That order probably stays the same even with the regular shitty weapons, but as part of a good, organized squad I would be willing to rotate positions. A distant 4th would be anti-tank, and bringing up the rear would then be sniper, support, and engineer last-just the ultimate in waaay too specialized and underpowered.