I prefer ,308 because I believe ammo, may be easier to find and I will be using it in a second rifle (semi~auto for plinking etc,), but from my research on ballistics I believe that the 30~06 carries a little better accuracy and energy beyond 400yds but the ,308 has a slight advantage before 400yds,,,
If I were hunting moose 30~06 deer ,308, but really the performance is very close the30~06 can be found more commonly with higher/heavier grain bullets,,,
Hope this helps, but you really can't go wrong with either for hunting,,,