.308 for me
Hunting as in deer hunting, mine's .308.
My first .308 was a M88 Win, an heirloom from my Grandad. I've also got a Savage .308 Scout. Not a hunter, but there's a whopping big Savage F-T/R rifle in the safe too!
Really, more power than I need for deer (150 lbs avg), but the reserve is there for bigger game if the opportunity ever arises. The M88 is a classic, the Scout is great for GP, and the F-T/R is much more accurate than I can shoot (consistantly).