Joe Warren was very accomplished. In college Hendricks was a 2 time National Champion, 1 time runner up and 4 time All-American. Maybe the most accomplished college wrestler in the UFC.
Matt Lindland got a silver in the Olympics as well as other awards. He could be the most accomplished.
You are forgetting a few big names. Koscheck was better than Hendricks also. But Askren or DC are probably the best pure wrestlers