Its easy to prove who has the best back and thats Dorian
This is a quote from Arnold Schwarzenegger from The New Encyclopedia of Modern bodybuilding
When a bodybuilding judge looks at a competitor's back , there are three things he is especially interested in in : ( 1 ) The thickness and muscularity of the upper back:( 2 ) the sweep and width of the lats and ( 3 ) the definition and development of the lower back and lower lats.
Dorian's upper back - traps are thicker & denser than Ronnie's especially his lower traps
Dorian's lats and Ronnies are about equal in terms of sweep and width again at their respective bests is probably equal , you can argue over centimeters all you want but neither in my opinion are noticeably wider than the other
Dorian lower back is simply in another league compared to Ronnie like the traps this is what separates Dorian's back from Ronnies , Dorian has better lower lats period , they insert lower into this back and they're much more developed and defined , his erector spinae are much sharper and developed than Ronnie
this is exactly why Dorian has a better back , Ronnie is comparable but Dorian is the better of the two.
p.s and both are comparable in terms of development & detail of the infraspinatus and teres.