I use Pyrodex in any thing I can not use Blackhorn in. So far as I know no one can say what causes the differences in crud ring but I live in the hot humid south and right at about sea level and I get it so bad that the gun has to be scrubbed between each shot or its not safe to try and reload it because I can not get the load to seat where as with Pyrodex I can shoot 4 accurate shots and the residue is soft so it is an easy clean. as the fellow above said it is easy by comparison to find a accuracy load for but they are comparable after you find that load.
Now for the other half of the problem, Sabotloader lives in the mountains around 5000 feet above sea level where the air pressure is less and the heat and humidity like we have here is nonexistent and he has little or no problem with 777, so what it comes down to is that pyrodex works for everybody and you will not know what 777 does unless you try it in your circumstances. Blackhorn will work for every body with a good modern TC [ Omega, Triumph, Encore ,Endeavor] and some of the other closed action inlines with good breach plugs. It shoots most accurate if you do Not clean until after you are done shooting.I my guns it shows better accuracy by far than any other powder besides not having to clean between shots.
There are several other powders but the only one of them worth mention is out of production. The others are very weak and attract moisture which makes them erratic.