1. Captain America: Winter Soldier
2. Guardians of the Galaxy
3. Avengers: Age of Ultron
4. The Avengers
5. Iron Man
7. Captain America: The First Avenger
8. Iron Man 2
9. Thor: The Dark World
10. The Incredible Hulk
11. Iron Man 3
NA. Ant-Man (not seen yet)
None are great, but Winter Soldier comes the closest. The simple fact is that most of them are competently made films that didn't turn me off. A few things to defend:
I've probably got Age of Ultron higher than most people. Personally I thought it was a bit better polished than The Avengers. Little things like Iron Man vs. Hulk not only being more fun to watch, but actually making sense. The rallying scene with The Vision paying off the Mjolnir bit from the trailers worked so much better than the forced "Remember Phil" stuff. The villain's plan was still dumb, but at least didn't end with a Phantom Menace shutdown of biological soldiers.
I really don't get why so many put Iron Man 3 ahead of Iron Man 2. Neither was my favorite by any means, but I found Iron Man 3's sins so much worse. Turning Mandarin into a joke, super powered Pepper saving the day, villain created because he didn't see Tony would rather be with the hot woman than him, Tony and the kid, not activating all those suits when his house was attacked, self-destructing his suits and seemingly turning away from Iron Man (then just showing up in Age of Ultron).
Iron Man 2 might have been rather pedestrian, but it didn't piss me off.
There's a big drop after my top 5 down to Thor. Which I give a lot of credit simply for not sucking. Seriously, I thought they were going to just look silly. All credit for finding Chris Hemsworth to put in that costume.
After Thor, the movies are "meh" at best. The first Captain America is little more than a commercial for The Avengers. Iron Man 2 a basic sequel. Thor 2 not terrible, but nothing I ever plan to watch again. The Incredible Hulk I've basically forgotten.