Someone beat me to it, but Herol Graham. Also mentioned Mike Hunter, saw him beat Ty Biggs. Biggs himself was a slick amateur, great skills at that level. Tony Tubbs had great skill at 'catching and countering' which may not have been appreciated by everyone. Maybe another worth a shout was Michael Watson ?
I would hate to say he wasn't great but certainly someone that is overlooked is Jose Legra. Billy Graham also Stevie Johnston
I'm not sure if he saw him live Eddie. In the early thirties Harvey came up our neck of the woods to fight a local hero and tough guy "Cast Iron" Jack Casey. The fight was for the British Title at The St James Hall in Newcastle and apparantly it was a humdinger with Harvey having to call on all of his skills to get through. My Dad said there was one point where Casey had Harvey badly hurt but Harvey had a reputation for feigning being hurt to lure his opponent in and Casey held back thinking he was bluffing, much to my old mans frustration whenever he told the story, so I tend to think he was there. He did fight out of the same stable as Casey as a young lad. He always waxed lyrical about Harvey though.
Reigned mostly in a really really horrible division. I think there are a lot more worthy of being a great. His resume just isn't very good. Jorge Linares is one with a sublime offensive skill set. But already mentioned.
I'm going to add Miguel Angel Gonzalez. I thought he had an airtight game skillwise, not the typical Mexican styled fighter thrown to the wolves as a pro but developed more in the amateur game.
One who comes to mind as well is Chris Byrd, he had some fantastic defensive skills and at a lower weight class I bet he'd punch just fine as well. Not a great heavyweight but a very good one.
Like the Tony Tubbs reference he had some great skills the weight was one problem and the cocaine was an even bigger one. Also deserving of mention is Greg Page who seemed to have all the skill in the world yet rarely was able to beat solid competition. Dokes is another one who had some great skills but wasn't great. Buster Douglas also comes to mind.
Duke McKenzie.very skillful textbook boxer not a big puncher but took titles at three different weight classes.Not to shabby.