[Anizeb]

ARMA, or at least ARMA II, is very far from realistic. They aimed too high and shot too low.
There's a lot you can do, sure, but damned if nothing works as intended.

Battlefield is better in terms of both functionality and realism, although the multiplayer maps are too large for their own good. They look terrible.

Call of Duty, on the hand, has the opposite problem. Their maps are too small, they're not diverse enough. (MW3 is an exception however. Their maps are actually quite perfect, if a little boring in small groups.)

But in reality, I'm not a fan of any multiplayer FPS. It's a genre that's essentially the same, no matter what the game is. I like fresh gameplay, so games that are effectively duplicates of each other just don't do it for me.

That said, an FPS that focuses on the campaign mode rather than the multiplayer mode is much more interesting. MW3, again, isn't as bad as the others. The story is actually somewhat captivating.

(The only mass FPS I really enjoy is Black Ops Wii. Damned if that isn't fun.)