Anyone that would choose a bow over a .22 for defensive purposes has seen one too many Rambo movies.
I don't advocate choosing it first always, but having had a full conversation with a guy bleeding from two .22lr holes in his chest while waiting for the ambulance I'm not impressed.
Anyone who thinks they are going to head shoot "bad guys" that are interested in taking you out better be practicing an awful lot.
Yes I know the arguement for using a .22lr and yes I have several and some ammo. Overall, I think larger caliber, popular ammo will be more valuable. Not attracting attention to yourself and how well stocked you are would be smart, however it's achieved.
I've not heard of anyone living through being shot with a bow. Then again, most bow shooters only shoot game or targets. Porch monkeys provide a lot of data on the effectiveness of handguns and ammo.