I own the first call of duty (for Mac) and CoD4:MW currently. My college had opened a gaming center in my last years there, and while I worked there I got to try out MW2, W@W, and CoD:BO on both the PS3 and 360 (whichever was free at the time). As a side note, I loathe the PS controller, cheap plastic in a shape that gives my hands cramps, more like a remote than an ergonomic extension of my hand.
I think CoD4 is awesome, I've got several buddies that still play it, and in general we can't stand the newer games enough to own them. Can you say red tiger camo and all challenges complete? LOL! My strongest "NO" in the series was MW2, it took killstreak chaining rewards to game-breaking levels IMO; seems like if you camp 7 kills you have a good chance of stringing together a nuke. Hello Quiddich, where's the teamwork and gameplay in that? WaW multiplayer didn't actually bother me: seemed that the main problem people had with that one was that they were sick of WWII shooters. I ended up playing CoD:BO the most at the Media Sphere; the pistol wasn't a viable weapon most of the time, but I liked the maps and new features (Theater, Game winning kill, Zombies, new stuff to unlock) and it didn't feel like killstreak rewards dominated gameplay like MW2 did. The only thing is, I can't get my one friend to get it, and I've heard that once you actually get to set it up on your own equipment that the audio is more of an experience than a major tactical gameplay component. A lot of the guns are "meh."
MW3 gets its own paragraph, because I've bought & returned it twice. It's got all the new features from the games leading up to it, and the gunplay and controls finally feel as tight as CoD4. Problem is, it just feels like a stale game, and despite the new maps, unlocks, killstreaks etc. I just would rather play CoD4. I had plenty of time to learn the maps and find the "hot" zones, but I can only think of a few spots that allow me to flank the enemy, I only liked one or set of perks for assault while support perks + an LMG just made life too easy. Team DM was just boring. I returned it for Skyrim (which I haven't had time for yet), and later bought it again because our group was considering migrating to it & we were sick of all the hackers that plague CoD4 in its dwindling days... and returned it because it just doesn't feel like it's worth the $$. And when I went back to BF3, I saw EA had changed everything to rental servers, so that game feels like a chopped up version of what it once was.
So I'm not happy with any of the current gen FPS games, which is a shame for my favorite genre. I've been playing a lot more Halo: Reach lately, and while I can't dominate like in CoD it does feel like there is more purpose to holding or rushing parts of the maps and variety in gameplay roles. I actually have more hope for Halo 4 than CoD:BO2 to feel like a fresh game, but I'll probably try both in the hopes of being proven wrong. Here's hoping Treyarch has the right stuff to not feel like the "filler" Dev studio anymore.
