Shamrock, I suggest you get one with a good weight to it that will fit your life. Like I'd love to have a 3 footer again, but w younguns in the house it just aint practical for me right now since I have to keep mine hidden when not in use, so mines a medium size.
I prefer a glass bong thats heavy enough to not tip over everytime my cat flicks her tail at it. And I like to be able to see through the glass to see how big of a hit I'm brewin. And I like the shaft to be tall enough that I don't get a mouth full of spray every time I hit it. Get the slide out bowl, instead of a carb. And you might want to make sure its easy to clean.

good luck and show us what you get