I've been watching since 1991, I've seen those matches. I stand by my statementI know you just recently started watching and don't know what you're talking about, but Vince seriously was a consistently part-time professional wrestler for several years, unlike someone like Vince Russo or Michael Cole. Watch one of his matches, particularly his match at Armageddon '99 or Vengeance '03; he wasn't a very technical wrestler, but he was definitely a wrestler.
Wrestled a few times and had 4 Wrestlemania matches = wrestled hundreds of times and a dozen mania matchesIf you're a heel and the fans are cheering you, it means you did your job wrong, and thus are a bad heel.
The answer to the original question is Vince McMahon, BUT since I guess he doesn't count as a wrestler despite having wrestled hundreds of times and won the damn WWF Title, won the Royal Rumble, had about a dozen WrestleMania matches...
I can only comment on what I've lived to see, so based on experience I'd say that Triple H in late 1999-2000 is the most hated heel I've ever seen as far as legitimate seething hatred from an audience. He wasn't cool; he wasn't funny; he wasn't a badass; he was just everything a heel is supposed to be, namely a TOTAL DICK. Fans wanted to see him get his ass kicked...and mind you, children, this was before he legit married into the family, and thus the heat was totally based on his talent and not on any political extracurricular crap. The dude was such a hot heel, he had Al Snow getting babyface pops bigger than anything Cena's ever gotten when Al almost beat him.