Current CM Punk, SES Punk, and 2009 Randy Orton.
After Punk sang Happy Birthday to Rey Mysterio's daughter in his SES run, he became massively hated. He was a great heel during that time as well. Current Punk is also a very good heel. That fake heart attack skit had to make him the most hated man on the roster.
2009 Orton was an excellent heel, due to the fact that he had an intriguing character. He was the most dangerous man on the roster at the time, and he wasn't even a super heavyweight. He played the sadistic heel character perfectly back in 2009.