1st pick is GNR, They have some of the most memorable songs ever (Welcome to the Jungle, Sweet Child of Mine) and songs you can just plain ol' bang your head to (Paradise City is pretty much an anthem of THIS generation for some reason :D)
Slash & Duff McCagen (probably spelled his last name wrong... srry Duff) Were some of the best in their game, while Axl was a great rock vocalist (Although he's a ... you get the point.).
My favorite classic rock band.
Second is Ozzy. I really don't understand what made Black Sabbath so great, but Ozzy's music is just better in every way. From fast paced classics like Crazy Train and Bark at the Moon, or any of his other various hits I can't think of right now, he's a legend. Also, unlike GNR, he's still relevent today. Scream Like You Mean It is an EPIC song.
There was so many good ones in this category; it was hard to choose. Aerosmith and AC/DC are my runners up.
BTW Mrdaycee, can you give them some credit and have Foreigner SOMEWHERE in this competition? It's too early to beg, but I just wanna make sure you don't forget how awesome these guys are.