A 100g slick trick on the business end of a GoldTip 5575 shaft will zip a hole in a hog in a sec...Oh wait, you asked about rifle calibers...
There are many centerfire cartridges to choose from. Do you have a rifle or access (borrow) to one already? If the numbers are .27 or larger you're good to go.
If you're going to buy a new rifle, ask yourself how often will you use it? What do you plan to hunt? It's hard to go wrong with a 30-06 or .308. If you're not going to hunt a lot then maybe consider a .300wsm. It'll be more than enough for a sheep or hog, and if you ever want to go for something larger (elk) or farther (mulie or goat) then the flexibility would be nice to have.