IMO - .45 unless you plan to actually hunt with it.

10's have a bit more power, but .45's are a bit cheaper to shoot factory loads and have a much larger ammo selection. Plus should SHTF, .45 ammo will be around.

For a light packing gun, check out the 3" Springfield XD-S single stack. Safe, small, light and enough rounds to put down most anything out there.

Good luck with your decision.
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