I've recently come to concede that Reign in Blood is Slayer's finest moment. With a couple of stipulations.
1) Show No Mercy comes, very, very, close to matching it in quality.
2) Greatest metal album of all time? No.
3) Most certainly does not excuse Slayer for all the awful trend hoping they did from 1995-2005.
I listened to three Babymetal tracks...sounds like Chun Li getting butt-fucked by Andrew W.K. That's not something I ever wanted to hear.