Norseman and I have been having powder discussions over PM, but we wanted to offer it up to the membership, because a lot of folks could benefit from the info, and a lot of folks have something valuable to add.
First priority for this powder is it's gotta be clean. I will be shooting my .223, and 300 AAC Blackout almost exclusively through a suppressor. I don't want to gunk up a $1000 can with dirty powder. I'm a little paranoid about taking care of my Class III stuff. Cost is a secondary concern. It's gotta meter well in a Dillon powder measure.
I'll be loading mostly 55gr FMJ for .223. I'm working up m own loads from scratch for 300BLK because it's so new.
Norseman recommended Vihtavuori for cleanliness. Again, I'm taking that into consideration, but I'm open to other viewpoints.