When chosing a "best" powder there is an evil side to powder choices. Powders put out different ammounts of heat for the same volume
I recently became aware of how hot R#15 and Varget burn in a custom 308, 22/250 AI, and 17 Rem. I will pay great dividends in saving throat wear to choose a cool burning powder by heat index.
Of course, hunting requirements where a guy shoots 60 rounds a year are different than high volume shooting.
I saw fire cracking in my 22/250 AI in less than 100 rounds using Varget, and have since switched to AA2700. 308 Krieger was cooked by Varget, R#15, and N550 had to use special abrasive to get the carbon out of the barrel. N133 and N135 were my hunting powders in a 223 bolt guns in 223 Ai with 50g and 55g bullets, respectively...these powders are HOT! 223 bolt guns, I changed out to Benchmark with the 55g in the bolt guns at 3450 fps, and use Win 748 with 50 and 55g bullets short range coyote and colony varmints.
AA2460 and AA2520 are remarkable in 308's and 223 heavy bullets, along with many 243 mid weight bullets, they are cool burning(heat index) with a burning rate near IMR 4064.