Very tough... just going 80s on (lets remember folks wrestling started before 1980, Buddy Rogers, Gen Skandar Akbar, SuperStar Graham, & Ivan Kolloff were all massively successful bad guys, Harley Race too).
Post 1980 I still say NWA Champ Ric Flair - the matches, the promos, his ability to get a crowd totally behind anyone he wrestled was impressive. His promos alone during this time were unreal, the skit where he dressed a dept store mannequin to look like Jimmy Garvin's valet Prescious (who Flair was obsessed with in the story) and proceeded to strip its clothes off while showing just what would happen to her on their "date", even by today's jaded been there done that standards that was crazy. The interview where Ricky Morton smashes his sunglasses after Flair gives him a training bra because Morton cant get a "real woman" was hillarious. He also cornered the market on catch phrases like no one until The Rock... "whats causin all this", "Space Mountain", "To Be The Man...", "Diamonds are forver & so is Ric Flair", "Bleed, Sweat, & Pay The Price", "Walk Down That Aisle", "You gotta walk the walk not just talk the talk" - I remember falling off my chair when I heard Dallas Cowboys coach Jimmy Johnson use that last line in an interview about an upcoming game, his catch phrases were becoming a part of the accepted sports vernacular!
Roddy Piper deserves credit because Hulk Hogan doesnt get nearly as hot early on without him. Every good hero needs a good nemesis and Piper was the first real heel to battle Hogan, and he was so good at being entertaining and bad he truly made you want to cheer for Hogan. If Race & Dusty Rhodes helped make Flair & Flair made Sting and Brett Hat helped make HBK Piper helped make Hogan, possibly more than any other opponent.
A lot of guys were good as heels, DiBiase, Blanchard, Rick Rude, Jake Roberts, HBK, Triple H but those two above are my picks for best in the last three decades.
Give some props to Hollywood Hogan though because without his heel turn The NWO does not become the phenom it was.