Low time to kill of Call of Duty by far. Halo took me early on for online multiplayer in Halo 2, but after playing COD I have never liked long time to kill nearly as much.
I think it is more realistic forces you to be less reckless and watch your and partners back more while also being more realistic to real combat. Still I love variety and think Uncharted 3 does it right as well as Halo, but I never liked Battlefield at all as a military shooter.








