When I first finished NieR Automata, I went back over all the songs from the soundtrack and listened to them again. And again. And again.
That said, they aren't very Rock Band compatible, so there isn't much of a way to fit them in to customs. But linked to Weight of the World was a metal cover someone had made. That, I think, could work very well in RB. The song in question I've linked at the bottom, it's from their YouTube channel.
The same creator ALSO covered the Japanese version of the song, and uploaded it very recently, which sparked my desire for this song once again, also linked here.
Lastly, I'd like to recommend basically everything this guy has done. Every one of his covers just blows me away. He's done several Game of Thrones song covers, some WoW covers, and even Dragonborn, the menu music from Skyrim.