Re: Best ganker hero?
If you think tinker is a good ganker, well he also kicks butt late game. His nukes may not be as powerful, but with items he becomes one of the most ridiculous heroes. I think VS, ES, SK, batrider, all are contenders. Sven too I guess. Anyone who has a decent stun early on, then people that just do lots of damage like tinker and bat. Or slow lots.
I think much more important than hero is player. There are loads of heroes that can easily gank and first blood, but you need to play them right. There are tiers of gankers I guess, but I doubt one is really the best, especially in "any" game.