Modern Warfare 1 was good
Modern Warfare 2 was some of the worst trash I've played this gen (seriously)
Modern Warfare 3 was surprisingly good. Better, even, than 1 in my opinion.
World at War was pretty good, though the American missions were dull. Russian ones were wicked.
Black Ops, I personally really really enjoyed, despite being completely bananas. I mean, hell, all the CODs, save for maybe United Offensive (still the best in the whole lot), were total batshit insanity.
I loved Bad Company 1, and it gets my vote for best military campaign this gen. It's just as batshit as MW, but it's not hyper linear and scripted out the ass, and it refuses to take itself seriously in any capacity whatsoever. It's hilarious and just a lot of dumb fun. Bad Company 2 was great as well, but it lost a lot of the open world flavor from the first game. Still wasn't as linear as a COD though, and it was still a ton of fun and had excellent writing.
Killzone 2 was fun, but it had a lot of dumb moments (Visari Academy) and the story was total bullshit, despite having all the makings of goodness. Killzone 3 was more of the same, but played better overall in my opinion.
Gears is cool I guess. Stop and pop gameplay got real old real fast, and the story is some of the worst trash this generation, but it's good for what it is.
I loved MGS4 with all my heart, excellent game with an excellent story with a not-so-excellent ending.
I thought Medal of Honor was sincerely underrated. It had a lot of dullness to it, don't get me wrong, but the stealth missions were fantastic, it actually had a good, realistic story behind it (the scene where the commander and the senator are having their disagreement was excellently done) and the mission where you're holding out with a few other dudes in the tiny house that's slowly getting torn apart by enemy fire as you get rushed from a mountainside was one of the single most intense moments of any campaign this generation.
The Saboteur was a ton of fun. It had a lot of "off" elements about it, like it's poor attempt at AssCreed traversal, but it was certainly greater than the sum of its parts. It was just a blast run around Paris as an Irish badass, murdering Nazis. Great artstyle and titties, titties everywhere made it a 30 hours well spent.
Ace Combat count? Haven't played Assault Horizon, but I loved AC6. Beautiful graphics, hectic combat. Great stuff. I've found myself jumping into free flight missions with no combat and just flying for hours. No, seriously. But I'm a bit of an aviation nut. I used to load up BF1942 lan games with no players/bots and just fly planes around.
Resistance 1 was a great mix of modern console and classic PC design mentality, as well as a great mashup of sci fi and real world storytelling. Resistance 2 was awful. Haven't played 3.
Halo 3 was boring, ODST was excellent, and Reach was fantastic.
That's all I can think off the top of my head. Overall best singleplayer campaign was probably Bad Company 1. Sorry for the tl;dr post.