I actually think this could be a viable consideration. Assuming it's clearly defined to mean the person most likely to maintain a civil discourse and present logical arguments even in the face of an overwhelming lack of support. A person that gets you to change your mind or a person that you can respect even in disagreement.Inessential awards
Best Debator - Unless everyone disagrees, I think this category can go. The Darksider/Sunshiner/Moderate awards cover this I think and generally one of those posters is arguing/debating the most.
Now, if it's going to be just be 'most argumentative'... IOW an award for whoever is most likely just to argue a point on emotion alone more for the sake of argument itself rather than furthering the discussion or presenting a bigger overall picture... THEN that is an award that I'd consider of little value.