IMHO - and agreeing with werewolf, if you were to be a handloader, the 10 might be a good idea, since YOU can control the "where's the beef" answer. I don't think you handload. The difference between a .40 and a 10 can be nasty on the shooters side.
I would suggest that unless you REALLY want the extra punch, et al, of a 10, you might be better served with a .40. There WILL be ammo in more places, and it should be cheaper. If you're a wimp, or over 55, don't go badder than the .40. Even then you might be better off with a .45ACP, because the .40 is not a lot of fun to shoot a LOT.
BTW - what do you want it for? Hunting? (what?), protection? (from what?), targets? (9mm). Both the .40 and the 10 are hard on the wrists, and hard to bring back on target for follow-up.
b-