There was an old AVX (XVA X-Men vs the Avengers) in 1987.

What got my attention is how the book presented the teams. As presentation to the story each team introduction gives you the feeling of what they are about, their background and who they are.

This is the Avengers Introduction.
The avengers saving the world and being heroes.

This is the X-Men Introduction
People hanging out.

And this is why I love the X-Men. Hope to see more of this in this days books, this kind of spirit is the what the X-Men were about. Which seems lost for a long time.