i would assume that KISS has sold more albums.
Bruce Springsteen
Kiss
No
megadeth has been out longer so im asuming them i dont know ive only heard the song that goes hello me its me again but their is a chance slipknot has
Kiss
That is a matter of personal preference, they have sold more albums/CD's than KISS.
Elton John sold more records than Van Halen. Elton sold over 300 million, whereas Van Halen sold close to 100 million.
Van Halen
Close to 110 million albums sold worldwide.
45 million
Julio Iglesias has sold more albums in Spanish language