Variety is the spice of life.
.30-06 with accelerators will take varmints, load accordingly for the size of big game from there. 7mm mag will also do the job if you're not selling the pelts.
Load and range should be within ethical specs for the game you are hunting using a rifle for everything. Don't take a 1000 yard shot on an Elk with a .30-06 when a .50 bmg will do the job better.
