308, 7-08, 7mm RM, 30-06, whatever. All are good choices, and for a beginner, really, all are suitable. To a newbie, the differences aren't all that big. Pick whatever you'd like, knowing full well that you're going to want all the others eventually, too.
Consider getting into reloading. It allows you to shoot a lot more (this is KEY to accuracy), allows you to tune your loads to extract the most out of your rifle, or reduce recoil, or whatever. It also makes the price difference and availability of factory ammo negligable. Reloading is not as expensive as you might think, and it pays for itself really quickly. It's also a lot of fun