As part of their "Greatest of All Time" celebration on Thursday, Billboard asked various artists to name the Top 5 artists, albums or songs in the genre to which they belong. One of the more interesting pieces involved Poison frontman Bret Michaels ranking the Top 5 hair metal bands of all time. As you would expect, the former Celebrity Apprentice winner did include his own band on the list, but put them at the bottom. Bret's favorite hair metal band ever is Guns n' Roses, and he called their classic debut album, Appetite for Destruction, "one of the best rock n' roll records ever." Behind Axl & co. Michaels listed Def Leppard, Bon Jovi, Motley Crue and Poison.  To check out the rest of Billboard's "Greatest of All Time" coverage, Click Here.