I am heavily biased in favor of locust. Not only have I taken more punches from locust than any other wood, it's made all my best shooters-- whether that's from my experience with the species or the woods stiff, snappy nature is hard to tell.
Sure, in a test where I had to take one stave of either Osage or locust I'd take the Osage 'cause I'm no dummy. If I could take five of either wood, on the other hand, I would take the locust to make the fastest bow I can.