Shop around for something that appeals to you, the search is half the fun of a new rifle.
I love my Marlin 30-30 lever action, and I also find single shots to be appealing (black powder rifles are my latest quest.) You won't know what want until you hold a rifle that fits.
As far as calibers there are too many to choose from, some of them have already been mentioned. I have a bolt action chambered in 308 win as a secondary and general purpose rifle.