What is a good caliber rifle to use for mainly for whitetail but also would be good for larger game like elk?

I am looking to get a new hunting rifle and I mainly will use it to hunt whitetail in PA, but I am also planning on taking some trips out west to hunt elk, mule deer and bear so I want something that will work on all. I have looked into the .308 and the .300 win short mag or the 300 rem short ultra mag but there are alot of opinions on all of these rounds good and bad. Just trying to get some other thoughts...can be about these rounds or anything else you think would be good.