if your going to use one rifle for deer and elk i would have to say the 30-06 because there is sooo many different grain ammo avaible. but i myself use a 270 for deer and a 300 win mag for elk.
.260 Remington
.270 Winchester
.280 Remington
.308 Winchester
.30-06 Springfield
.338-06
Other (please state in post)
if your going to use one rifle for deer and elk i would have to say the 30-06 because there is sooo many different grain ammo avaible. but i myself use a 270 for deer and a 300 win mag for elk.