It's hard for me to separate the characters from the films, so a ranking is a bit tricky. Additionally, within each "franchise" there is a great deal of variation.
For example, I think Robert Downey Jr.'s Tony Stark is the best character in the MCU, but the second and third of his individual films were a bit uneven (owing a lot to lack of interest in the villain IMO).
Ant Man suffers a great deal in the sequel which really didn't capture the magic and humour of the original (and a lot of the improvised dialogue apparently), so averaging them out doesn't do the "franchise" any favours. Guardians of the Galaxy was similar.
Meanwhile, the first two Thor movies were forgettable while the third one was wildly entertaining.
But I'll try anyway, in terms of how "good" the films are.
1. Captain America
Overall, very consistent. Winter Soldier is the best MCU film, Civil War was entertaining (I liked Bruhl's innovative approach to taking down the Avengers) and First Avenger was surprisingly good and touching.
2. Iron Man
I like the original 2nd best of all the films, and Robert Downey Jr., despite everything, can carry an MCU film regardless of how good it actually is. They're just fun. He makes any scene that he is in enjoyable.
3. Black Panther
They managed to pack a lot into one film, in terms of the atmosphere and setting, introducing Shuri and other characters, demonstrating T'Challa's rise to wisdom and challenge to the authority and legacy of his father, and a compelling antagonist. It had some funny moments as well.
4. Guardians of the Galaxy
The first film benefits from being such a positive surprise. I did not expect a tree and a raccoon to work. The second film did pretty well with the characterizations but the finale is just CGI overload.
5. Spider Man
Michael Keaton was great as the Vulture and I think Holland is the first live-action Spider Man that actually seems like Peter Parker. Maguire was too weird and Garfield was too mopey. I can see how some people might not like all the teen drama but I think it's a refreshing contrast and I like how they didn't rush to age him out of high school.
6. Avengers
I find it hard to evaluate "Avengers" because it's a different type of film, aside from CA: Civil War. With so many characters, it is a tricky balance. What I've found overall is that my original viewing represents peak Avengers and every subsequent watching makes it drop a bit in the standings. The time travel conceit was a pretty brilliant twist in terms of allowing the audience to revisit various moments in the MCU from different angles and perspectives.
I think if I evaluate it when factoring in the complexity of pulling it off, I might move it up to 3rd. But as standalone movies, I'd push them down a bit - sometimes there's just too much going on.
7. Ant Man
I really enjoyed the first film, it was sort of madcap and silly and the supporting performances were great all the way through. The sequel just didn't capture the magic of the first film and I'm pretty confident in dropping the franchise down.
8. Dr. Strange
I actually liked Dr. Strange a lot in the comics so I'm a bit biased. I think Cumberbatch does a good job and the Ancient One was well cast. Unfortunately, the villain is sort of bland (Vasillius? Was that his name?) and while Stephen's solution at the end was nifty, Dormammu was introduced with no real fanfare or understanding so he ended up just being a big stupid giant head in the sky. Mordo was being set up as a future rival but ended up just being a bit whiny.
I'm hopeful that the sequel pushes it up a bit.
9. Captain Marvel
Too much origin, not enough story. We don't really get a handle on the character at all. An amnesiac doesn't actually make for a very interesting person. I did like Ben Mendelsohn's turn as a good guy for a change. A lot of the humour relied on 90s references which for some reason I feel is cheating even though the soundtrack in GotG fulfills the same purpose with 80s music and somehow I give it a pass.
10. Thor
This would be much higher if it wasn't for Thor: Dark World (worst MCU film) and the so-so qualities of the first film. Thor: Ragnarok was a hoot.
11. The Incredible Hulk
I'd be interested to see Ruffalo try to carry a Hulk film. I just think he was a better and more interesting Banner. I had very little interest in the Norton and Bana films.
I wanna see his girlfriend. She looks fine to me.
