I am torn between WW296 and AA#9 for best accuracy in 44 mag. The problem with 296 is that they want you to load only full house loads. I like slightly reduced loads and powders like AA#9 and blue dot seem to work best for that.
I also shoot a lot of medium hot loads with AA#5 at around 1100-1200 for the 250-290 grain range.
I have not tried the WC820 powder yet.