I use mesquite...it's what we have growing locally.
DeShivs is right...it must be dried and to correctly do so it will take a minimum of a year, depending on the thickness you're starting with.
All fruitwoods are nice. Maple
might be slightly harder than oak, but certainly not tougher.
If you have a hardwood store up near you, go there. You'll find Padauk, Teak, Cocobolo, Zebrawood, Bloodwood, Irocote, Bacote, Ebony, various Rosewoods, Lignum Vitae, and the list goes on.......AND, it'll be dry and, after a couple of three weeks in your shop, ready to use.
EDIT: Look for pallets. I collect them down here because I cut them up, split them, and use them for kindling in our woodstove. I have actually saved many pieces of pallet lumber because I've found spalted and sometimes burled wood in them. Somtimes it's hickory or something unidentifiable, but there occasionally some very fine pieces of wood in there that'll catch my eye. Being a woodworker, I look for stuff like that, but only recently have I started to think about handle material for knives (hence the mesquite scales on my RAT-3)
