Totally depends on you. I've been brought up on .22, so it's what i'm used to shooting with. If you can, try to get a go of both, then see what suits you. What I would suggest though, that if you're new to hunting with air rifles, that whatever cal you choose, you get some good paper punching sesions under your belt, so when in the field, you can be accurate.
ye first i need to sort out my scope and then im goin straight back to hunting rabbits on my uncles land