It all depends on the application.What type of rifle,ignition,etc.For traditional rifles stay with pure good ole fashioned black gold.(aka black powder).I don,t shoot inlines so I can,t give an opinion on those.
Goex is the main brand and is the most readily available.Call around the shops in your area,you should,t have trouble finding one that carries it.Heck,I even bought some from my local Gander Mtn.,so check yours.What rifle and cal is your rifle?
My buddy got some777 when he bought his first flintlock this year, and it has a bit of a delay in firing. I tried it in my gun, and the same thing. I gave him some FFF, and it pops right off like it should.
Substitute powders (777, Pyrodex, Shockeys, ETC.) have a higher ignition point than real black powder. That is why they are on the shelves of stores like Gander, Dick's, Wal-Mart ETC. If you are shooting a flintlock, real black is a must, if you want consistant ignition. IMHO it is best for percussion sidelocks with #11 ignition also. The subs work best in inlines with 209 primers. 209 primers produce a hotter ignition, which is needed to ignite subs with consistency. You can order real black powder here: http://www.grafs.com. It ships to your door.