Of course you've gotta love Hulk Hogan - "I'm a Real American" and "Voodoo Child" Joeiss
. Other than that, my favorites are:
Million Dollar Man's
Mr. Perfect's
RVD's (The one he used before the one he has now)
nWo Theme
Bret Hart's
HHH - Play the Game
DX
Ultimate Warrior's
Ric Flair's
Undertaker's First
Boss Man's First
The Mountie's Second (The one where he sings. Granted he couldn't sing, but I still got a kick out of it.)