For me, most of the hunters listed don't last in games long enough to even measure their impact on a game. They leave at the first sign of adversity, slamming the letters A F and K with thunderous strokes reminiscent of what Haiti felt some years back. And Erotk? Rastaman? Who?
That being said, I had to choose between Sneaky and Discover. Sliquelolz was a close third, but he's more effective on his rogue. Sneaky's good on his hunter, I can admit this despite our past differences and rage fests aimed toward each other. He doesn't often shine alone though, at least not nearly as much as Discover does by himself. I know the game will be that much more difficult when he's on the other side.
Disco gets my vote, though I'm still going to /lol spam him all the way to the graveyard <3