I might have gotten in on this discussion a little late, but I will carry on. I got to thinking about this from a historical perspective, regardless of the inherent physics of different bow woods/designs.
If you were to ask, for example, a Welsh bowyer ca 1300 what the best bow wood is, he would say, unequivocally, "Yew!" Conversely, if you were to ask an Ottawa bowyer, ca 1800, he would say "Osage!" Similarly, a Hun would say "birch, horn, and sinew," and a Pacific islander would say "palm." (I'm sure you guys see where I'm going with this.)
So, historically anyway, the best bow wood is that which supplies the bowyer with the required properties, local climate compatibility, local availability, and familiarity. I am not going to discuss bow designs or limb physics (mostly because I am a rank amateur and am breaking just as many bows as I am getting finished and shootable), but Osage works for me because it's available (aka a noxious, tire-poking, fence-choking weed), climatically stable, and pretty forgiving. However, a bowyer in Oregon is going to use yew because it is available (though not a noxious, tire-poking, fence-choking weed), climatically stable, and forgiving to him. Same for any other available woods. A few people on this thread have said much the same: "the best bow wood is the one you happen to be working."
I will concede, theoretically, that osage seems to suffer from less cast than other woods, but it appears that given proper (or improper) design, any wood can have less cast, or more cast, than osage. Bows seem to be intensely personal things, so I would bet that 1000, 2000, 8000 years ago, many a spirited discussion over the best material has been perpetrated over a fire, or in a mead hall, or in a wickiup. Luckily nowadays we don't settle our bow making differences with a dagger or stone axe to the eye. (God, I hope not)
Just a bit of cultural/historical relativity to brighten the day.
