I have a really eclectic taste so its impossible for me to choose just one favourite.
I love Queen, Meatloaf, Franz Ferdinand, Kanye West, Maroon 5, Madcon, The Feeling, Flo Rida, Eminem, Kenny Loggins, Michael Jackson & loads more, they are just the main favourites :D
Though the best song ever has to come from the Rocky Horror Picture Show team, I love the Timewarp :D