These are just the first 21 movies, not including Avengers: Endgame of Spider-Man: Far from Home. These are my opinions and mine alone.
First tier here are like the really excellent movies. Basically A+ through B+ movies.
1. Guardians of the Galaxy - Hit me right in the perfect nostalgia point.
2. Black Panther - I can't add anything. I thought it was near perfect.
3. Captain America: Winter Soldier - Same as Black Panther, just T'Challa was a bit more.
4. Thor: Ragnarok - I have too much fun with this movie. Just the sheer insanity was worth it for me.
5. Avengers - It was the original crossover that's never been done before so it needs to be here.
6. Captain America: Civil War - It's flawed, but damn... That airport battle.
7. Guardians of the Galaxy Vol. 2 - Didn't get me as strong at GotG v1, but still enjoyed it.
At this point, we're at what I considered good. Basically B+ through C+
8. Captain Marvel - I don't care what the haters say. I really liked it. It ain't perfect, but I had a tons of fun with it!
9. Captain America: The First Avenger - I have a soft spot for period pieces, like this, the Rocketeer and even the Shadow.
10. Avengers: Infinity War - This was a big and impressive deal and it deserves it's accolades. Though it's only half the story, so... Number #10 on the list.
11. Ant Man and the Wasp - Both Ant-Man movies I just greatly enjoyed. I got nothing negative to say. They're just fun.
12. Ant-Man - Same.
13. Doctor Strange - Yeah, it's basically "Magic Iron Man" origin, but it was trippy and fun. Plus the "I've come to negotiate" scene was awesome.
14. Iron Man - The movie that kickstarted it all. It was really good for it's time. Now it's just a decent movie.
15. Spider-Man: Homecoming - I gotta be honest, once he got rid of the high tech suit and went to his normal suit? I loved it. But otherwise, I was kinda... Itg's okay.
And the average movies. C+ through D+. I don't think there's an outright failure of a MCU movie. Even the worst is still better than other's best.
16. Avengers: Age of Ultron - This should have blown my brains out about how awesome it could have been. Instead... Meh.
17. Iron Man 3 - Hasn't aged as well as I thought it would. I like it, but I'm not rushing out to see it again anytime soon.
18. Thor - Yeah... It's Thor. It's okay.
19. The Incredible Hulk - I appreciate how it handled being a sequel to the 2003 Hulk movie and was a reboot at the same time. (I'm kinda doing the same thing.)
20. Thor: The Dark World - I won't lie. Darcy saved a lot of this movie for me.
21. Iron Man 2 - It meant well, but that ending kinda sucked.
And just for fun, here's my choices on the MCU TV side of things. (I did not include Cloak and Dagger on here, because I just haven't seen it yet.)
1. Daredevil - Season One and the first half of two was amazing. The second half kinda wasn't, but S3 was awesome again.
2. Agents of SHIELD - I could write an entire essay about this show. Look, I understand why you might have left early on... S3 was REALLY bad. But with S4? It turned itself around and never stopped kicking everything and everybody's asses.
3. Jessica Jones - Season 1 was fantastic. Season 2... Less so.
4. Runaways - It's a decent show. I got no real issues with it. I just wish the whole Disney-Fox deal was done sooner so Molly could still be a mutant.
5. Agent Carter - Like Jessica Jones. Season One was great. Season Two, less so.
6. Luke Cage - Season One was great... Until Cottonmouth was killed. It never regained that momentum.
7. Iron Fist - Season One is actually a great corporate board room drama series... Unfortunately, it was hyped as a martial arts show. S2 was way better.
8. The Defenders - This SHOULD have kicked all ass. It should have been the accumulation of all the previous five seasons. Instead it was a sequel to Iron Fist's lackluster season one, and the parts of Daredevil that wasn't fun.
9. Punisher - This is unfair, but I never saw Season Two. Season One was just... It dragged for me. I feel like it would have been the show that the younger, more angrier me would have liked, when I was 15-20 years old. But with more relaxed and less angry me in my 40s? It has it's fans and I appreciate it, but I'm not one of them. Sorry.
10. The Inhumans - The only Marvel show I never finished. Even adorable Lockjaw could not save it. (I'm hoping that AoS gets him next season, since Gregg Clark said that Lockjaw was his favorite.)
And in case you're curious... The Fox X-Movies
2. Deadpool 2
3. X-Men: First Class
5. The Wolverine
And you can scatter the rest wherever the hell you want. (Though I would place the Legion show at 4.5 for Aubrey Plaza alone.)
The Sony Spider-Movies are even easier.
1. Spider-Man 2
3. Amazing Spider-Man
4. Spider-Man 3
5. Amazing Spider-Man 2
And if you're wondering where Spider-Man: Into the Spider-Verse goes? Way up top, above Guardians of the Galaxy 1. It's become my favorite movie of all time.