Round one: Best thrash album

Which one is better? Kill 'em all, by metallica, or Rust in Peace by megadeth? Vote by
posting your opinion!

The battle

Its been going since Megadeth was founded. Both are two of the big four Thrash metal bands.(Anthrax, Slayer, Megadeth, and Metallica) They are both great bands in my opinion. But i want more peoples opinions. I personally like metallica better, but dont get me wrong, megadeth is a great band.