What a clusterfuck of a thread this is turning out to be. 
Heh, yeah. At a glance, I knew it'd be a, "No, NO! Dorian's arms sucked! He's not one of the most genetically gifted!" Substitute Dorian's arms for Kai's waist, Sergio's conditioning, Arnold's hamstrings, Haney's arms, Robinson's thickness, Ronnie's calves -- etc., etc.
Purely in terms of genetic gifts, Sergio would seem at the top of the list. Dillet is up there for the sheer size of his limbs. Levrone and Padilla are up there for gaining back shit at a crazy rate (among other things). Ronnie, Dorian and Haney all qualify because each of them came in shredded at about the same height and over 250. Arnold's great for looking a shitload heavier than he actually was, in addition to decent balance.
What about guys like Phil Hernon, Phil Hill and Roy Callender? Thick as bricks and I don't recall any of those guys lacking anything.
A top 10 list is pretty much impossible to nail down unless you very,
very narrowly define WHAT genetic gifts you're talking about. Dorian is, in some sense or more, one of the most genetically-gifted guys because plenty have taken similar drugs and/or trained in a comparable fashion, but who looks
anything like him? Few.
But maybe I'm wrong and Dorian took X quality drugs at Y greater quantities than anyone else, thus explaining his fairly unique look. Unfortunately, unless his kid is doing the same thing, Lewis Yates looks a LOT like his daddy in certain poses, only smaller.
I know drugs rule all, but this genetic shit counts for something too. The guys who are huge as a result of drugs alone are like the fucker in those pics with the funny belly button, pec and biceps tear that people bandy about Getbig. Or some psycho like Palumbo in his heyday. Huge, yes. Shredded, yes. But just a big mess of bullshit stacked atop more bullshit.
Why didn't drugs transform the Palumbos and such into Olympians? God knows Dave abused the shit out of everything under the sun, so the simplest answer is his ilk didn't have the genes for it.