A do it all rifle for what range shooting? I could argue/defend a few calibers but if doing any sort of long range shooting, I would vote for the 7mm mag (or WSM).
If big game is the primary target with hogs and small game as the lesser included, I would vote for the 338 Fed or Win mag.
Nothing wrong with a .300 mag (or WSM) though either as a happy-medium. So many good options! That's why nobody owns just 1 rifle....lol