Updated the list as of 7/2019.

Updating post-Far From Home:

1. Captain America: The Winter Soldier
2. Spider-Man: Homecoming
3. Thor: Ragnarok
4. Black Panther
5. Avengers: Endgame
6. Iron Man
7. Spider-Man: Far From Home
8. Captain Marvel
9. Guardians of the Galaxy
10. Avengers: Infinity War
11. Ant-Man
12. Doctor Strange
13. Captain America: Civil War
14. The Avengers
15. Captain America: The First Avenger
16. GotG Vol 2
17. Iron Man 3
18. Ant-Man and the Wasp
19. Thor
20. Iron Man 2
21. Avengers: Age of Ultron
22: Thor: The Dark World
23. The Incredible Hulk

And 1a. remains Into the Spider-verse

Spidey FFH might be placing Top 10 due to recency bias, but I did really enjoy it and especially Mysterio.

When Endgame hits availability for me (waiting for 4K Blu-Ray) this whole thing might need to be revised. I think it maybe elevated some of the previous films.