Win.748 as well.If you look in the sierra reloading manual you will see that Winchester powders are most accurate especially for longer ranges.I have heard that Varget is very good as mentioned but I myself have not tried it yet.
WCC 844 and AA 2230C both work very well and are cheap. They are visually identical and the same loads chrono within 20 fps; I think they are the same powder.
I use Varget now, after starting with IMR 3031, never again! I use the Lee powder measure and I kept cutting kernels and getting inconsistent loads, so I switched to the Varget and it works really well.