Without going into great detail and a lot of typing, I'll just say the .30-06 offers the largest selection of Ammunition ranging from Varmint loads to Big Game cartridges.
As far as Rifle Brands Go, I think I'd go with a Ruger, the M77 has proven to be a great success and helped establish a great reputation for the Ruger company.
Are there other brand rifles just as good? Yes
are other calibers just as good as the .30-06? Yes
I suggested the .30-06 caliber and the Ruger Brand simply becuse of their proven reputations and nothing else.
Good Luck and Best wishes on which ever Choice!
Democracy is two wolves and a lamb voting on what to have for lunch.
Liberty is a well-armed lamb contesting the outcome of the vote.