I have my specialty powders, but the most versatile powder that I have and loaded in the widest range of cartridges...wait for it...Unique. No surprise there. I've load Unique in 38, 357, 9mm, 44 Special, 44 Mag, 45 ACP, 45 Colt, 30/30, .308 Winchester, 45/70, and 12 Gauge shot loads, 12 Ga slugs.
Unique may not be the absolute best, but it is acceptable in a wide range of applications. This stuff is unique, it must have been given to us by the Aliens.