It really depends on what you want the lure to do. Softer woods like pine, cedar, basswood, etc. have faster actions and higher buoyancy's. denser woods like maple, oak, ash, hickory, etc. have slower actions and are more (yet not) neutrally buoyant.
It also depends on what you're fishing for, muskie and pike would destroy balsa baits, but some hardwoods might not be appropriate for smaller panfish.
Think of your application, target species and method of use before you decide on a type of wood.
Cheers,
o2l