30'06 is the only thing you should consider, because all Americans should own one. FMJ for varmints, one of the millions of 30'06 hunting loads availiable for everything else.
You did not state what type of firearm you are considering, 30'06 is usually availiable in most hunting types of firearms.
The 30'06 is often called the "Mother of all cartridges" for good reason. Most of the other carts. mentioned have been derived from the tried and true '06.
Start here and then add to your collection: Remember you can never have to many guns!!! ( no matter what your wife says ).


Regards, gao