There are alot of Avengers series out there with Avengers Academy and Secret Avengers to name a few but I am reading The Avengers and Avengers Assemble that I have talked about on here. I like the team of the Avengers Assemble a little more that The Avengers team but I do like how on the Avengers comic the team members do change around some but they normally keep a good core group on the team. Cap, Iron Man, The Protector, and Spider Woman.
Having said that in The Avengers latest issue a lot of new faces show up from other Avengers teams. If I remember correctly The Protector and Cap have been the only 2 in all 26 issues. Also The Vision has came back so thats pretty cool. So if I were to rank them...
1. The Avengers
2. Avengers Assemble