All personal preference, this list. This doesn't have any particular order either.
All Ghillied Up
If you thought that I'd not include this mission, you're kidding yourself. This mission set the bar for all stealth missions. In fact, no stealth mission has come close to this level of good except for Vendetta. The convoy section scared the crap out of me.
Speak of the devil. This mission was really good. The only reason I would put it before All Ghillied Up is because you get caught half way through. Then it no long becomes a stealth mission. But waking up in the fountain, taking out the enemies at the beginning over the sound of German bombers, the game of cat and mouse. Nostalgia trip, man.
Of Their Own Accord
Now you might question me for this pick. I remember back when this game was old news and I had just gotten it. I didn't know shit about the story. Never saw the trailers or anything. I was also a little younger at the time. Like maybe 14. And you know when you were playing a CoD story at that age, and you didn't know what was going on in the story, just that you had to shoot people, move up, shoot more people, repeat? That was me. And I remember playing through the campaign thinking, "Oh, I'm in another county shooting up people." It didn't really dawn on me that we were in America until this mission. I remember walking out of the bunker in the beginning, looking up at the Washington Monument, and thinking, "Holy shit...." It just shocked me.
Vorkuta... 'Nuff said.
I wasn't too big a fan of MW3. That being said, this mission really stuck out to me. Not just because the main protagonist dies, but because the person you've been playing as has been there from the beginning. I remember wanting to go back to CoD 4 and killing Makarov instead of Zakhaev. I'm kinda glad that they put that Easter egg in MWR.
Karma was an interesting beast to me. You're on a floating city where the worlds population of the 1% live, and you need to find a weapon. The weapon is really a woman, and you need to extract her. I really liked the look of the city, the club section, everything.
I don't know why I like this level. It might be the betrayal. But I'm leaning more towards the fact that this whole level was mostly a tower defense. The weird thing is... I hate tower defense levels. So I don't know why I like it.
Ok, this level scared the shit out of me. It just had a really eerie vibe going for it, and I fucking loved it for that.
This level in my opinion was CQC at its finest. I liked everything about the level. The betrayal, the CQC, the challenges, the Access Kit weapons, everything.
This is the only campaign level with zombies in it to date, and they don't call me Zombie Hunter for nothing. I've played this level countless times just for that segment. Not to mention the nice W@W throwback.
So, yeah. That's my list. What is your favorite level in Call of Duty?