For centerfire, just 3:
.223 (mostly through various ARs) ground squirrels, coyotes, deer, whatever.
.308 for Mule Deer, Elk, Coyotes, targets, whatever.
.300 Win Mag for ranges where the .308 runs out of steam.
With that said, I honestly think a guy could very easily do everything with 2, like a .223 and a 30-06(or.270/.280,6.5 Swede, etc), but as a long time .308 and 300WM shooter, I am very happy sticking with my old standbys.
