There really is no "best powder". I had this conversation with a couple friends of mine this weekend. A rifle will like a specific bullet and bullet grain, a rifle will like a specific powder, primers ehhhh I haven't really seen a rifle be picky. Yes that may sound weird but its true.
Yes a rifle will fire with what ever right combination of correct powder and bullet brass and primer. But to get to the root of reloading, is you either want to save money or better accuracy. A lot of people want both.
So when you want both, they have to expirement. Get yourself a manual, take it to a shop, look to see what powder the shop has to offer for sale(not sold out) and buy 2 or 3 pounds, and try them to see what you and the rifle come up with.
What ever powder your not happy with, you can sell it or trade it for what works in your rifle.
My rifles like IMR4895, Varget, CFE223, H380