Avengers - Relatively solid plot, good characterization, and the only one that didnt feel the need to overstuff the show with cameos. I didnt need to see Odin announce to Thor that Loki is on Midgard, and so they didnt show me Odin announcing to Thor that Loki is on Midgard, he just shows up in a thunder storm.
Age of Ultron - A film that has a weird quippy robot for an enemy. Why Ultron? The trailer was so much better than the actual film. Why treat Baron Von Strucker as a joke? The rest of the films treat Hydra seriously, so its just weirdly out of place when you just write this guy as a complete loser. Quicksilver shows up and is anti-climatically killed, and is rarely mentioned since. The scenes with Vision are all great.
Infinity War - A good film that is ruined by the Soul Gem scene, which is just lazy writing to create some drama, and the Red Skull is by far the most gratuitous cameo in the entire MCU. Why him? Other people abused the infinity gems, hell they knew what they were, the Red Skull just had the tesseract.
Endgame - A stereotype of everything wrong with the MCU, hey why have your big moment be a dramatic moment with character where you can just have a big flashy scene where you just put "Please Cheer" at the bottom. The Portal scene is better out of context. The highlight of the film was Thor screaming at a child and threatening to murder him because of Fortnite. Time heist itself was good so its better than Age of Ultron.