Let's see: Iron Man, Quicksilver, the Scarlet Witch, a really pi--ed off Vision returned from the trash heap & those dastardly Inhuman terrorists...
I vote Wolverine, Spider-Man, SpiderWoman and Cage! (and Ares in advance!) oh, and the leader would be Bendis Bendor; motivated by money and ego, the nafarious Bendis Bendor (sic) Assmeble's a team of top dollar money grabbers and 3rd string I-can-make-us-famouse heros for adventures beyond what any fan can dream of! The Masters of Evil, the dark, Hlaiburtonish Anti-Avengers, they're going to make you pay!
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I've been out of the loop so long I don't know which villains are still alive or still evil. As the Thunderbolts showed, it doesn't take much to take out the New Avengers, just some teamwork. A bunch of Nazi Girlscouts could knock 'em flat. How about a team of true egomaniacs that could challenge even the best Avenger team ... Graviton, Nefaria and Ultron. Who else would you need?
Every Masters of Evil (or villain team in general) needs at least one clearly bad membership choice.
But I think realistically you could add someone like the Absorbing Man. He's the sort of guy who can contend with whoever is on the Avengers line-up and the solutions to beat him are always interesting.
I've never wanted to see a Masters of Evil that only had big guns. I've always preferred a collection of mid-range villains that are more effective becuase of their teaming up. I would love to see the Crimson Cowl/Justine Hammer given a chance to live up to the legacy, but barring that, I'd love to see the Enchantress make it as a big-time supervillainess. Give me a mix of classic villains, too: Absorbing Man/Titania, Klaw, Living Laser, Whirlwind, and, uh, someone techy. Maybe the Parnell Jacobs War Machine?