This thread is evil for making me choose just one. >:(
But if I have to, I'll go with...the original tune. For the nostalgia and funny parodies. Remember singing it all the time way back in the day and annoying the crap out of my parents.
Pokémon World, Pokémon Johto, Born to Be a Winner, I Wanna Be a Hero, Unbeatable, We Will Be Heroes, and Battle Cry - (Stand Up!) also rock.