my personal favorite was mw2. if it weren't for mw2 I probably wouldn't be playing cod now.
i LOVED The m4A1, that's the best all around weapon they've ever had. also the Barrett .50 was awesome. dual umps with rapid fire, steady aim, and extended mags. that's the only call of duty you can make that kind of setup. I used to snipe ppl from almost across the map with the dual umps. fun as hell. the storyline was wayyyy better than anything trey arch put out. ever. and the spec ops mode. two player multiplayer on extra missions. that stuff was cool as hell. it actually promoted offline couch multiplayer. and last but definitely nowhere near least, it had the little gallery after the game to run around in. it looked like a museum, and I remember there was something you could do that I think sent enemy troops but don't quote me.
about black ops..... everything seemed a sepia-tone. like it was all a shade of brown or tan or something. and things seemed a bit cartoony for my tast, especially after MWx. however, pure is by far the best game mode ever- I do hardcore now so I probably won't play too much-, and the console at the start menu with the game info and the gorilla arcade game was cool as hell. the story line tho? your telling me I just spent 4-8 hours of gameplay with reznov, building a relationship with this guy, swapping stories, etc. and then just bam!! it's all in my head and I'm crazy. that royally angered me.