Boy, this is a tough question. It is like watching models walking down the runway and asking which is the most beautiful.....beauty is in the eye of the beholder.
That being said, I have used BLC-2 and had some success with it, but I've also used IMR4198 and IMR 4895 and I suspect that there are a slew of people that have used other powders with great success. I have an affinity for ball powders, especially if I'm using a powder measure to throw charges because it doesn't catch as much.
I think the only real answer is "whichever powder works best for you, in your rifle". Probably sounds like a "cop out" answer, but I think it is the truest one.
Roudy