30-06 is what I chose for a number of reasons.
1) I needed that caliber in the safe because it is so versatile, and what self proclaimed gun nut doesn't have at least one 06.
2) It can reach out there and touch something.
3) Ammo is everywhere and fairly reasonably priced.
4) I wanted to get started in this long range stuff with out breaking the bank (yet) on a full custom 338 ultrawhizzbanger or 22 eargensplittenloudenboomer.
5) It will kill anything within the ranges I feel comfortable shooting at an animal(less than 500 yards).
6) Recoil is mild enough for those days at the range where lots of powder is burned.
So I chose a 30-06 basically because it is a good learning tool that can fill more than one roll for me.