Guardians really is a perfect demonstration of the Marvel formula at work -- without clouding judgment with an iconic lead character.
Winter Soldier is the only Marvel movie that felt grounded (at least until the super climax). That scene with Fury in his car is perfect, the bunker, the brilliantly choreographed street fight, the elevator....
And Infinity War is just an amazing rollercoaster ride that has almost no down time and ends with the ultimate cliff-hanger. And juggling 24 characters like that is an impressive feat in its own right. I still think it is the most re-watchable of the MCU.