I'm not very well versed on rifles but I'll chime in on that. Many go with a .270 or .30-06 for a number of reasons. First might be availability. With those two rounds you have an endless choice of manufacturers and models of ammo. As far as North American game, you could take down most species with those two short of maybe Grizzly bears and Moose?

7mm Mags kick like a ****ed off mule. At least that's been my experience