I'd like to completely revise my list:
Top 10 (in no particular order)
Demogoblin
Doppleganger
Shriek
Carrion
Kang the Conqueror
Mandarin
Falcon
Baron Mordo
Dormammu
Tiger Shark
Box Sets
Outlaws: Puma, Prowler, Rocket Racer, Will O' the Wisp
Enforcers: Big Man, Ox, Montana, Fancy Dan
Wrecking Crew: Wrecker, Piledriver, Bulldozer, Thunderball, Excavator
West Coast Avengers: Tigra, Firebird, Mockingbird, Vision (silver version)