X-Men: First Class is one of the best X-Men movies from the franchise, and I don't think that's a question. It's up there with X2: X-Men: United and X-Men: Days Of Future Past, but one of the things it did perfectly was the dynamic between Charles and Erik. They were written wonderfully, and the acting by James McAvoy and Michael Fassbender was amazing. They start out completely different, but come together as people with common goals, but over the course of the film, their paths diverge and so do their ideals, but they still maintain that respect for each other. Obviously, that didn't originate in First Class, but First Class did it so perfectly, so when the time comes for the MCU's X-Men, they should certainly take notes on how First Class did the dynamic between Charles and Erik.
I hope that the MCU X-Men movies take notes from First Class on the dynamic between Charles and Erik.