On the surface I could see someone reflexively picking Furnas on this status as a Can Am alone. The fact that he was an extremely impressive offensive wrestler who had some of the smoothest spots around also works in his favor.
Having said that I don't think this is a run away win for Furnas. I've never seen any Furnas from Knoxville (at least not that I can remember) so I may be missing something, but I don't recall him ever being that impressive as a singles guy. He has a really awesome match with Van Dam from ECW, but amazingly it's Van Dam's bumping that carries the match. His other really good singles match is that Windham match from the Clash and from memory that is a carry job.
Great tag wrestler and he's been in too many excellent matches to rate him behind Punk, but if we were looking at singles v. singles I think Punk would win this.