I have shot deer with .223,.243.2506,3006,7mmRM,300WM and .338 WM.All were the best or worst.It depends on. 1. What can you shoot accurately and comfortably(so you'll practice,practice) 2 What kind of conditions,terrain your hunt in.In Montana I can be in wooded river bottoms,brush choked coulees or wide open sage flats or stubble fields in the same morning.My fast,flat open country deer iron might not be best at close range in the brush.As I get older I am leaning away from the magnums.My next rifle will be a .308.Always wanted one.I get tired of the old argument of "I need something that will penetrate at 400 yards, facing away,last day of the hunt,trophy of a life time".If you can't guarantee that you'll be able to kill the deer cleanly,don't shoot.It's that simple,it's hunting not killing.I have hunted with lots of people in the last 25 years and I would say most of them are way overgunned.By this I mean they can't handle the recoil so they don't shoot enough.I shoot 5000 to 6000 rounds of centerfire rifle ammo a year.It makes one familar with the rifle and the more I shoot the better I get.Sorry I'm so preachy this morning.