Unranked within each tier:
Avengers: Age of Ultron
Iron Man 2
Captain America: The Winter Soldier
Captain America: Civil War
Guardians of the Galaxy Vol. 2
Guardians of the Galaxy
Thor: The Dark World
The Incredible Hulk
Captain America: The First Avenger
Iron Man 3
I can't remember for sure whether I saw First Avenger or not, but I definitely caught ten minutes of Iron Man 3 while theater-hopping. I slept through pieces of Thor 2, which probably helped elevate it over the original Thor.
I'll be making an effort to see the new Spider-Man and Thor, partly because they both had decent trailers (the new Thor promises to be the best of that series so far, partly because it seems largely villain-less; just like Cars 3 looks to be the best of that series, because it seems largely Mater-less), but also just because I like being a part of the conversation.
So I've seen 12/15, and half of those get a mild recommendation from me. I wouldn't have to include any films I dislike to generate a top five, though my general cutoff for a Top 5 list is films that grade B or higher, so I'd consider this a very weak top five. I think of these movies less as films than as episodes of a really expensive tv show. And like with most tv shows, the range of quality hovers narrowly between passable entertainment and not quite successful entries. No real highs or lows. Most of these films have lost my interest in their third acts, when they should really be at their most exciting. Poorly imagined villains are largely to blame, but their are other issues as well.