If I had to pick just one maybe the .308. I tend to gravitate towards the older standards and U.S. military rounds. 30-30, 9 para, .45 ACP, 5.56, 7,62x51 and I have a Browning A-Bolt II in 7mm Rem Mag for the really reachin out stuff. Have yet to go past 300 with it yet but I will one day. Other calibers also but those are my go too’s.