Here are some of the calibres I currently own: 22rf, 204, 6BR,7-08,6.5 x 284 and 300 win mag. Most of these are full custom rigs, a couple with carbon barrels. If I wanted to reach out and touch things I would say it would have to be in 30 cal. But for general hunting, the 7mm and 6.5mm personally I think are the boys. The 6.5 has a huge selection of bullet types and weights, has huge BCs and very good penetration if you look at ballistic gelatin tests. So I will go with a 6.5, even the venerable 6.5 x 55 is still hellish popular
Rich.K