While everyone has their own opinion on this, I agree with the above. With the small caveat that I'll allow a step down in bore to a .277.
For me, the ideal range is 6.5 PRC as the bare minimum of available energy (even though I'd prefer a little more frontal area than that .243 provides) and 7 RM as the max acceptable recoil. That sweet spot allows for a great selection of calibers. If you need to stick with ammo at your LGS, you've got 270 Win, 308, 30-06, and 7mm RM. (You could even cheat 7mm-08 in there by accepting a tiny tick down from the 6.5 PRC.) If you're willing to reload or just buy online, you've got 6.5 PRC, 7 SAUM, 280 AI (my personal favorite of the bunch), 270 WSM, 280 Rem . . . and even more if you're willing to delve deeper into the obscure, defunct, and esoteric.