The list in the linked thread is probably one of the worst rankings of movies I have ever seen, but it did make me ponder how all those movies should be ranked. This includes ALL Marvel movies, not just the MCU ones. This is not my personal ranking of the movies but is rather a numeric-based approach. I looked into critic scores, audience scores, and a combination of the 2 and looked at how all these movies rate in relation to each other and it ultimately resulted in the following list which I have also broken into tiers. I understand everyone will have their own preference, but I fell like this gives a pretty accurate overview of how all of these movies rate in relation to each other.
TIER 1 (top rated by both critics and fans)
1. Spider-Man: Into the Spider-Verse
2. Marvel's The Avengers
3. Guardians of the Galaxy
4. Logan
5. Iron Man
6. Captain America: The Winter Soldier
7. Captain America: Civil War
8. X-Men: Days of Future Past
TIER 2 (rated at least above-average by both critics and fans)
9. Avengers: Infinity Wars
10. Black Panther
11. Spider-man: Homecoming
12. Big Hero 6
13. Thor: Ragnarok
14. Deadpool
15. Doctor Strange
16. Spider-Man 2
17. Guardians of the Galaxy Vol. 2
18. X-Men: First Class
19. Deadpool 2
20. Ant-Man
TIER 3 (average to above-average ratings by critics and fans)
21. X2: X-Men United
22. Ant-Man and the Wasp
23. X-Men
24. Avengers: Age of Ultron
25. Spider-Man
26. Iron Man 3
27. Captain America: The First Avenger
28. Thor
29. The Amazing Spider-Man
30. Iron Man 2
TIER 4 (below-average ratings by critics and/or fans)
31. Thor: The Dark World
32. The Wolverine
33. Blade
34. Venom
35. The Incredible Hulk
36. Blade II
37. X-Men: The Last Stand
38. The Amazing Spider-Man 2
39. X-Men: Apocalypse
40. Spider-Man 3
TIER 5 (rated bottom tier by either critics or fans, but not both)
41. X-Men Origins - Wolverine
42. Hulk
43. The Punisher (2004)
44. Fantastic Four: Rise of the Silver Surfer
45. Blade: Trinity
46. Daredevil
TIER 6 (bottom tier by both critics and fans)
47. Fantastic Four (2005)
48. Ghost Rider
49. Punisher: War Zone
50. The Punisher (1989)
51. Ghost Rider: Spirit of Vengeance
52. Howard the Duck
53. Elektra
54. Fantastic Four (2015)