Before I built my build off bike, I got some advice from the president of the Dog Town Chopaderos.
He basically told me that what ever you want to build should already be in the frame that you start with. (A cruiser frame isn't good for making a straight angle chopper looking bike, and so on...)
So I would just say to visualize what you want to build & then try to find & frame that can be tweaked to your vision with minimal work.