they're not necessarily better. Especially after a certain point where they are to big to clear comfortably. I think that the most important thing is the dynamic between the size/shape of the chamber and the size of the bowl, and the amount of water it holds. There's some small bongs you can get really huge rips off of and there are large ones that aren't so great.

I think one to one and a half feet is a good size, but I have one that's six inches and it hits really good too....anyway, my answer should by now obviously be that I don't have a fucking clue.