For 250's, any powder in the 4895 range will work, whether R15, Varget, TAC, H335, 4064, etc. Slightly slower powders that have small granules would also work, such as H414/W760.
The same powders will also work with 286's, but the slower-burners tend to get more velocity, such as Big Game, 4320, H414, etc. Big Game I what I normally use, but apparently it's hard to find right now.
