I think that this thread is slightly off.
To perform well in a debate takes a few key elements, the top two in my opinion are:
1) Knowledge, or the ability to fake that knowledge convincingly.
2) Language skills, yes including spelling and grammar.
On KMC I think that very often one of these is lacking.
I would have to say the person that appears to have a decent amount of knowledge, or at least fakes it better than most if he doesn't have it is Janus. I believe he also tends to have a strong grasp on his language skills. There are a number below him, but Janus has yet to make a post I can really come away from saying now that was just the most stupid thing I have ever read. I have come away from his post wondering, was that all BS? But I was unable to really consider his post bad all the same.
I do not necessarily believe he is the best, but my experience with him shows a better method of reasoning than most.