I did a full re-watch before Endgame.
- Incredible Hulk is the only one that felt really weird / bad / pointless. Besides the role being re-cast, you also have Betty NEVER coming up again, Hulk being effectively re-introduced in Avengers making his Origin movie less essential than Cap and Iron Man. Incredibly Hulk is the only one I would full-on dump into a "SKIP" category as the library of films grows bigger and bigger.
- Even the commonly agreed-upon "bad" movies like Thor 2 and IM3 are still fun to watch in the moment and are perfectly serviceable as stand-alone superhero romps. They're both odd-fitting in MCU canon and have iffy villains, all the usual complaints, but as pieces of "summer movie" entertainment they aren't bad.
- One interesting thing I learned on my re-watch is that movies I USED to think were bad, lime Iron Man 2, are enriched by all the MCU movies that follow. IM2 used to feel SOOOO bogged down by all the world-building a SHIELD stuff that's shoe-horned into it. But now that there's a dozen movies that came out after it that build on that foundation, it doesn't make its inclusion in IM2 feel as out of place any more.