I'd go with a .308. My dad has had one for 30 years and its the only rifle he owns and its killed many elk, deer and antelope. I bought a .308 last year and shot my first antelope with it and that boy droped so fast! Then right after that i dropped one of the buck's does (i had two tags). And i shot my first buck with a rifle with a .308 (i mostly bow hunt).
The .308 is like a 7mm/08 but from what i heard the .308 is better. The .270 will drop a moose and an elk with ease.
The .243 is a good caliber, but out here in Montana it wouldnt get much use sept for deer, coyotes and pronghorn. Wich might be good if thats all you hunt but i wouldnt even think of shooting an elk or a moose with one.