I use a manual powder measure and never found Unique or any flake powder to be a problem. Not quite like the "pouring water" of ball powders, but not an issue when my standard for coarse metering is IMR stick powders.
Since I load for handguns chambered for .22 Hornet, .221 Fireball, .222 Rem, .32ACP, .30-30, 9mm Luger, .38 SPL, .357 Magnum, .357AMP, .44SPL, .44 Magnum, .44AMP, .45ACP, .45 Colt, .45 Win Mag, and .45-70, I use a variety of powders, including some rifle powders.
The powders I used when I began loading back in the early 70s were Hercules, and eventually Winchester. For my uses I could easily get by with 4 powders (not counting the rifle rounds I load in the Contender)
Bullseye (or W231, either one) for a fast powder, Unique for middle level loads and 2400 and W296 for top end stuff. I include W296 because its is just slightly better for max loads in my magnum semi autos than 2400. I use 2400 for top loads in my revolvers.
There are several other powders I use, Red Dot, and AA No.9 for a couple. I've used many other powders, but nothing that wasn't on the market during the 80s-90s, I just stopped bothering to try the newer stuff. So I won't comment on them, even if they've been around 20 years now, or more.
Run what you can get, I know things are still not like they used to be.