GotG 1 is in my top 5 MCU movies, I can watch it over and over. Part 2 was kinda meh to me, but Part 3 is better than 2.
Iron Man 1 is up there along with Winter Soilder. Avengers and Infinity War round out my top 5.
Spiderman 1 and 3 are both also great. In fact I could argue Spiderman 3 could replace Avengers in top 5.