I'd like to give honorable mentions to Kerry Von Erich vs. Jerry Lawler at Superclash back in the late 1980's, and Spike Dudley vs. Bam Bam Bigelow at the second ECW PPV in 1997. During the latter, I was very worried about Spike's health, and for the former I was a mark and very scared at the amount of blood coming out of Kerry.
I was thinking about it, and I think Mr. Perfect was the first heel I ever cheered for. I know I was a Demolition fan before their face turn, but so were most people and, hell, that's why they did the double-turn with the Powers of Pain.