Guerrero is for his division equivalently better than the tough but limited Murray. Thurman's opposition has been a tad better. Thurman's division is a bit thicker as far as talent, then the devoid middleweight division also.
GGG comfortably. Murray top 5, Geale and Macklin top 10 at the time plus quite a few top 20 fighters. Thurman has had a debatable top 10 win in Guerrero and after that its Bundu or Chavez who are struggling for top 35
Thurman is big enough to fight GGG and even if GGG would have to come down He'd stop Keith "run time" thurman.
You can't go by rankings when one division is clearly much more talent laden then the other. Middleweight is barren, while Welter is thick with talent.
Guerrero is a 4 weight division world champ with wins over other top champions. What has Geale and Murray done? The talent level in WW is clearly much deeper than MW. I love Golovkin but Murray is a journeyman.
Even, but Golovkin stomped through his guys much more convincingly and shows WAY more talent in the ring.