Resistance and Liberation looks pretty cool. Might give it a shot.
Regarding ArmA 2 and Red Orchestra 2 - I've been looking at these 2 for some time, at this moment I'm dissapointed in my computer, my processor is quite old and can't run neither of those. Darn!
S.T.A.L.K.E.R. games are great, the weapon handling is a great improvement over other games *coughcallofdutycough* where you can empty an entire clip without even moving your mouse and still be able to hit one spot. It's not exactly what I'm looking for, but these games are still great. HOWEVER, Gob, you are wrong about the fact that S.T.A.L.K.E.R. 2 is coming out. It was cancelled, and GSC (the creators of STALKER games) remade their company, called it Vostok games (Vostok, as in the place of Ukraine), and started a new post-apocalyptic survival MMO. Think DayZ meets STALKER + something.
America's Army - Well, I was dissapointed in AA2, so I'm not so sure about AA3. It just felt too... Too arcadish, yet realistic. It's like somebody threw together Call of Duty and added suppresion effect, made weapon damage times 3 and voila, you got a game that got me nowhere. Let's not even get started about the fact I couldn't find a single server that didn't have some kind of a mod installed on top of it.
A.V.A doesn't seem to be exactly what I'm looking for. Maybe I'm just prejudging, but it looks more like a skill based shooter (which isn't that bad).
Heroes and Generals looks promising, if it has come out of beta phase, I might give that a shot.