My wife watches all of the Marvel stuff. I watch some of it. My favorite artifact from the Marvel Cinematic Universe is the television series Agent Carter with Hayley Atwell, so my wife has been bugging me for years to watch The First Avenger, which features Carter/Atwell's largest part in a Marvel film. I finally broke down, and I'm glad I did.
It's a standard movie for much of its length, more like a James Bond movie than an Avengers movie, and I mean that as a compliment. After a decade of these movies, it's refreshing to watch one with only one hero (well, one plus Agent Carter). I have actually enjoyed most of the movies I've seen from the Marvel Cinematic Universe ... I thought Black Panther was a terrific movie, Spider-Man: Into the Spider-Verse also excellent (although I'm not sure it's in the Universe), and outside of the Guardians of the Galaxy movies, which didn't do much for me, I've found something to like about the rest. And it's no small thing to keep a series going as long as Marvel has without cranking out stinkers.
But outside of the two I just mentioned, I have no real desire to watch the Marvel movies a second or third time. They're better than OK, but they aren't great.