Well said, and he definitely is the contender for that honor.
The way I see it, there are about 3-4 Siths who qualify for that honor... but those Siths have very little way of comparison between them.
Plus there's not much info about them that can give us the tool to "pit" them against each other.
Tulak Hord was also one of those lords where people said they were the greatest combatants of all time, but all of those, including Ragnos, had lots of people say that.
All in all, between the cream of the cream in lightsaber dueling skill, those 4 are miles apart from the others, and maybe I should have added that to the piece - however, measuring them all, I thought Tulak Hord had a little bit less than the one I chose to star in this article.