A buddy of mine was given a 6mm as his first deer rifle when he was 12. He hunted with it for 15 years and killed plenty of deer. Excellent deer rifle and super accurate with little recoil however the .243 would be my choice due to a better selection of ammo. Either way you can't go wrong.
Ballistictip, I came back to this post to say just that, but you beat me to it! That's a very good point. I always had some struggles finding my 6MM ammo. No doubt that it's an awesome caliber! Long live the Remington .244! (6MM)