I'd say GSP, Hendricks, Cormier, Jones, Romero, Askren, and Velasquez are the best I've seen (not in order).
Koscheck, Rashad, Weidman, Sonnen at 185, Nurmagomedov, Edgar, and Mendes also great.
Would maybe add King Mo to my 'also great' list here. The way he used his wrestling vs Jacob Noe was perfection.
I'd say GSP, Hendricks, Cormier, Jones, Romero, Askren, and Velasquez are the best I've seen (not in order).
Koscheck, Rashad, Weidman, Sonnen at 185, Nurmagomedov, Edgar, and Mendes also great.
I think GSP is a fair choice for best MMA wrestler ever....
....but it's a myth that he dominated Koscheck in the wrestling stakes. Re-watch the fights. GSP wins both fights comfortably, but the wrestling is very even in both. GSP can't do anything with Kos in the rematch, their wrestling cancels each other out and GSP wins the fight by superior striking only, and in the first fight GSP dominates the wrestling early then has that reversed later in the fight. Maybe GSP edges the wrestling because if I remember rightly his dominance in the first fight lasts longer, but in no way can it be fairly stated that he "dominated" Koscheck in terms of wrestling over both fights. It's a myth, contradicted by the evidence at hand.
GSP.
The real question is who is the second best MMA wrestler of all time.
Prime GSP without a doubt But jones does have great wrestling too
GSP still one the fight & that was after multiple acl surgery he had... No dought in my mind that Prime GSP dominates Hendricks