I've always wanted to go to the Download Festival and Gigantour. I've already been to Lunatic Luau, Ozzfest, Vans Warped Tour, Day Off Fest, Mayhem (2x), Uproar and 98 RockFest in Tampa. As you can see, the ones that I went to were hard rock/heavy metal. It all depends on what genre you like.
The Newport Folk Festival is the best because it gave us Joan Baez, Peter Paul & Mary, Phil Ochs, Tom Rush, Pete Seeger, Odetta and more. Also because the fans booed BOB 'ELECTRIC' DYLAN when he abandoned the genre in favor of his nasal rock. Take in both the Newport Folk Festival and the Newport Jazz Festival and you will see the best music on earth.