First three that I thought of; Survivior Series 2002, Wrestlemania XIX, Vengeance 2005. All great PPVs. Worst? Judgment Day 2004.
Yep - it was THAT bad. It had Moredcai vs Scotty 2 Hotty on the card ffs. Awful. Chavo vs Jaqueline was pretty crap, Rene Dupree vs John Cena is one of the worst matches in recent memory, Booker T vs Undertaker was devoid of any drama or emotion and the main event was absolute crap until the bloodbath began. The idea of Bradshaw being in the main event was preposterous; he'd done nothing to earn the title spot at all.Seriously? Judgement Day 2004? Looking back it was ok. But it had one of the most incredible main events I ever saw.
The absolute worst PPV ever is KOTR 1995. Ridiculously bad. A showcase of everything that was wrong with the company at the time. So much talent, yet some of the most fucked up booking ever. They even managed to turn Shawn Michaels boring. The main event was Savio Vega vs Mabel. The lowest point in WWE history.
That or heroes of wrestling, which had Jake the Snake acting like he was masturbating with a Snake. Man he was fun while high.