I gotta say Black Ops. Based on real events, one of the best campaigns of all time.
yea Cod 4 and MW2 were good tooI played the original on PC back in the early 2000s, and that one was so much fun, but I would have to say my favorite was CoD4 Modern Warfare. That came out when I was in high school, and I logged so much hours on it. Also broke a couple of controllers playing that game lol. Thankfully I dont get that worked up anymore about games.
CoD2 and MW1. But I'd say Spec Ops: The Line is probably the first and last military shooter I'll recommend other people to play instead of CoD, for reasons better left unspoiled.