It's easy to get sidetracked by the information overflow on the web, and the nuances that distinguish similar cartridges, firearms and actions. But in reality, unless you are very experienced and practiced these differences are small and often are more than outweighed by convenience.
When I was considering moving up from a .223 bolt to something larger, I looked hard at the three (and more) that the OP considered but ultimately was swayed by convenience, price and availability. For my still-early phase of shooting, being able to shoot more, try a wider selection of rounds and to choose from a wider selection of rifles chambered for a given round were all more important than whether the 270 shot flatter than the 308, or the 30-06 could reach out a bit farther than the 308.
I chose the 308 and a Tikka Sporter and never looked back. It's been a great step and I clearly don't know what I'm missing, if in fact I'm missing anything at all.
B
