Mike,
Just about any good quality hardwood will do fine. The tone will definitely be subject to the type used, but different, not necessarily better or worse. I've used maple, ebony, cocobolo, milo, mahogany, and mango, to name a few. All of the ukulele sounded nice, but different.
What kind of tone are you looking for? Generally, the harder woods like ebony and rosewoods will give good fullness and sustain, while woods like mahogany and maple will tend to be more clear. Something softer like mango will be sweet.
What are you using for the sound board? Spruce will match nicely with a hard wood. If you do mahogany, I would go all mahogany, for the sides, back, and top. Not to say that mahogany doesn't sound good with a spruce top, I just prefer to do an all mahogany, if the build is leaning in that direction.
Aloha,
Paul