How far away do you plan on shooting? Keep your shots to 400 yards or less and a 270 or 308 will do the job. A 30-06 might stretch the effective range to 500 yards, one of the 300 or 7mm mags are good for 600 and the 338 Lapua is a 700 yard elk killer.
I'm not good enough to shoot farther than about 400, so I'd be perfectly content with a 308, 270 or 30-06. Unless you have the skills to shoot at longer range the bigger guns are a waste, they don't kill any deader at closer range.