First off, yes I know they are completely different. I've been considering getting one the albums. So flood, decide for me. I will buy the album mentioned. I like foo fighters, and I like Guns N Roses. I know more GNR songs than I do FF songs, but I do like Sonic Highways opening track. I've also been meaning to get into foo fighters. TL;DR pick either GNR greatest hits or Foo Fighters Sonic Highways.