I've seen a few over the years, you just can't beat the live experience.
Greenday x 3
Guns n Roses
Linkin Park x 2
Metallica
50 Cent
Eminem
Lil Wayne
Simple Plan x2
My Chemical Romance x 2
James Blunt x 2
Brian Adams
Silverchair x 3
Blink 182
The Veronicas
Kelly Clarkson
Korn
Good Charlotte
Pink (coming up in a couple of months)
+ others I can't think of at the moment