Spies and demos are great at taking out sentries. Also scouts can take em out if you inch to the edge of a corner and expose a little bit of the sentry to your eyes and shoot it with your pistol. Pistol is actually quite effective in long range combat.
Most kills:
31 (as Heavy)
I guess I stated my comment wrong. Just because you get alot of kills with a class doesnt mean its too strong;(which is obviously what I accidently implied in my previous post) my valid argument is that his grenades have a large hitbox, its easy to hit with his grenades. You just need to aim slightly ahead of where the person will move and their dead meat... I heard people bitching about stickybombs too but I dont care lol. Nice heavy kills btw I never got that many XD.