re: What characters were the "main" avengers in comic books?

Just went to Wiki. Here are the current "teams":

Current Rosters
Avengers
Team Leader Maria Hill
Team Members Protector (Noh-Varr), Hawkeye (Clint Barton), Iron Man (Tony Stark), Spider-Man (Peter Parker), Spider-Woman (Jessica Drew), Thor (Thor Odinson) Wolverine (James Howlett), Red Hulk (Thaddeus Ross)

"New" Avengers
Team Leader Luke Cage
Team Members Squirrel Girl (Doreen Green), Iron Fist (Daniel Rand), Jewel (Jessica Jones-Cage), Mockingbird (Bobbi Morse), Spider-Man (Peter Parker), The Thing (Ben Grimm), Wolverine (James Howlett), Ms. Marvel (Carol Danvers), Victoria Hand

"Secret" Avengers
Team Leader Steve Rogers
Team Members Ant-Man (Eric O'Grady), Beast (Henry McCoy), Black Widow (Natasha Romanoff), Moon Knight (Marc Spector), Nova (Richard Rider), Sharon Carter, Valkyrie (Brunnhilde), War Machine (James Rhodes)