As much as I loved Egghead's Masters of Evil (Moonstone, Tiger Shark, Radioactive Man, Beetle, Shocker, Whirlwind, and Scorpion) the best version will always be Zemo's Under Siege Masters. That was a team put together with just one goal in mind and that was to @#%$ up the Avengers period.
Baron Zemo, Moonstone, Mister Hyde, Tiger Shark, Wrecker, Piledriver, Bulldozer, Thunderball, Blackout, Absorbing Man, Black Mamba, Screaming Mimi, Fixer, Goliath, Grey Gargoyle, Titania, Yellowjacket, and Whirlwind. Pound for pound strength wise that is one of the toughest groups the Avengers have ever gone up against. This team was all brute force.