Another guy seldom mentioned for this particular skill was Larry Holmes. He was excellent at it but all that ever gets said about him is the jab and his recovery skills.
If you consider Sammy Angott great, and I do, just about, then he probably edges Wlad out here. The greatest fighter who strategically employed clinching to a considerable degree, was Ali (Duran could hold and hit, but he didn't clinch, as such, very often), imo.
I don't know if he reaches the "great" class, but Rocky Castellani's fights bug me because of his excessive clinching. Sammy Angott has been mentioned already, but I'll mention him again because he was among the worst if not theee worst. Joey Giardello clinched a lot when he was not in top condition, which was about half the time. If was an official and a guy clinched alot, I would hold it against him when I scored the fight. I think it is a basically unfair tactic.
Lennox Lewis, he tasted a few good shots from Tyson in the first minute of the first round and knew how to tire him out, excessive clinching. Bruno tried to clinch Tyson prior to the bout but he got the receiving end, a couple points deducted before his willpower was deducted by Iron Mike. Also I wouldn't want to call John Ruiz great but man did he hold and clinch like his life depended upon it. I guess the Tuaman reprogrammed him.
The part about Duran...I believe he can be quite the hammer clincher at times,but yeah, he's mostly just similar to Hagler for most of the time,except he went to the inside more and starts faster.