Oh and skyrim
I don't think Skyrim counts as an FPS...the combat is poo (besides modded magic), the animations are poo (even with mods), and the voice acting is sub par. However, everything else is amazing, story, atmosphere, music, lore, open world, etc etc.
As for the OP, from my most played to the least played:
Battlefield 3
Red Orchestra 2/Rising Storm
Metro Last Light (no multiplayer but I'm on my second playthrough now)
Fallout New Vegas (admittedly, the FPS portion of it isn't why I play it)
Battlefield Bad Company 2
Call of Duty Black Ops
Call of Duty World at War
I have a bunch of others that I haven't touched in a while too. Battlefield 3 and Red Orchestra is more than enough to sate my thirst for FPSs.