Unique. It was originally released as reduced load rifle powder. I have pamphlet from Hercules from 1933 showing various rifle loads along with several older canisters marked rifle powder on them. It works in shotguns and pistols even better. I have personally loaded it in 218bee, 223, 30-30 303 brit, 7x57, 45-70, 35 rem, 357mag, 38spcl, 20gauge,30-06... well I can't even remember them all but suffice to say in every caliber I ever owned...
It is waterproof, doesn't decompose with normal storage, ignites easy, and has nice linear pressure curve meaning it is a predictable powder.
Some say it meters poorly but I never , ever had bridging problem. It is somewhat fluffy but that contributes to its inherent accuracy since it ignites easily and tends to fill more of the case.
Some say it burns dirty...are there really people who care that it burns dirty??? apparently and that amazes me....well anyway at lower pressures that is true but at higher pressures it burns clean.
If you want one powder that is useful across a wide spectrum then you will not find a more versatile powder than good old Unique