I started a favorite powder check off poll on thehighroad.org and I invite anyone who cares to participate to do so to help broaden the poll results:

http://www.thehighroad.org/showthread.php?t=584783

I've shot and have some of almost every powder mentioned but BlackMag, White Hots, Blackhorn 209 and Pinnacle.
I have preferred powders for different guns because quite frankly every powder has something to offer in the way of advantages and disadvantages.

For revolvers I like using APP.
For most sidelocks and shotguns I like using Pyrodex.
For hunting with #11 percussion cap inlines I've switched to using APP from using Pyrodex P.
I like using 777 in my .36 rifles.

I have unfired guns that I'm not sure what I'll use with them yet.

I prefer not to shoot with black powder. I have some but just don't have any need to use it yet. Maybe if I buy a flintlock or have a change of heart about which gun to use it in. But until then I would just as soon use old powders that I still have some of like Clean Shot and Clear Shot.

The same goes for 777. When I find a use for it in another gun then I will feed it to that gun. But I generally shy away from it. I'll probably end up shooting more of it in a revolver someday.