Full Specturm Warrior is fantastic but not really a first person shooter by anyones logic, its a squad based strategy game.
Operation Flashpoint and Armed Assault are both fantastic games and I love them both but their interface and control system in general still feels a little 'clunky'
Ghost Recon (the original) was fantastic, Advanced Warfighter (the PC version anyway) was just too awful to even start on (I wont go on but seriously, I could rant for a VERY long time about how much GRAW on PC sucked).
Rainbow 6 Vegas on the other hand is by far the best special ops game ever made on PC. But its not really a 'war game' as such.
Conflict Global Storm is tremendous fun but isnt really that hyper realistic, more action movie than war documentary. Same goes for C&C generals. Fanstastic game but not really all that realistic.
Then we have Combat Mission. If youve never played any of them I HUGELY recommend them, theyre fantastic games, essentially realtime, table top wargames with a worrying level of detail. If this game lives up to its predecessors it will frankly be a 'must have' title for any wargamer!