I think I've been coming up with Avengers rosters ever since reading Avengers 181 where the US government stepped in and imposed their own membership. Over the years I've probably come up with hundreds. Seriously, it borders on being obsessive compulsive.
The Big Three will always be the core of any Avengers team worthy of the name.
1. Captain America (Steve Rogers)
2. Thor Odinson
3. Iron Man (Tony Stark)
After that I love to see characters who have have never had membership, but who have had some association with the team in the past.
4. Goliath (Bill or Tom Foster)
5. Red Wolf (William Talltrees)
6. Amora the Enchantress
7. Leir, Celtic God of Lightning (obscure I know, but always thought he could be fun in a Hercules kind of way)
8. Black Cat (Felicia Hardy)