I wouldn't say Gordon's the best - I'd say being able to differentiate between what needs hunting and what doesn't is a key factor. Also, in the end he got himself turned into what he was hunting. Does that suggest skill to you?

Perhaps Bobby was the best. He had been hunting for a while, and I think he hunted alone too after whatever happened between him and Rufus. A lot of hunters turned to him for help. He's the one who was shown teaching the Winchesters about demon traps, and they said he originally taught John to hunt.

i get your point. he screwed up and turned. can't be the best. i'd say dean is the best hunter at the end of the day. close second would be bobby