It is hard to find “better” than IMR 4895, H4895 or AA2495 (which is Accurate Arms copy of IMR 4895) given that the 308 cartridge was designed with IMR 4895 as the propellant. Then M14 was designed around the cartridge.
There have been other powders, if you want to try a ball powder try AA2520. That was very popular in the 80’s when it first came out.
I have buds who use IMR 4064, which is a stick powder. IMR 4064 is a longer stick powder than IMR 4895/H4895/AA2495, so it does not throw as well. That does not mean anything if you weigh your powders. IMR 4064 is as slow as you should go in a M1 or M1a.
I have tried IMR 3031, works great, N140, that also works great.
If you want to find the “best”, you will just have to experiement with different powders in your rifle. Just don’t hot rod it, as you can see from the inset, military cartridges were not magnum loading. Just keep your 150’s 2700 fps or less, 168’s between 2550 and 2600 fps, and your 175’s at 2550 fps.