Thor is a founding Avenger but he's treated like fodder.
Writers talk about how much they like him but all he seems to be good at is knocked out. The low point of this was him being knocked out by his own lightning in Secret Avengers.
In fact, he's the only founding Avenger that got his butt kicked in AVX.
The Avengers these days is basically Captain America/Iron Man and the other superhero these days.