I would say Country Life's pantothenic acid. I really don't have much to compare it to but I found it to be very effective. I was taking it a year or so back and had to stop taking it. It was making my hair feel too thick and weird. It's hard to describe but I didn't like it. I was taking 500mg twice a day for about a month. I'll see if I can find the thread that I posted about it on. It was a while ago though.
I just started taking Country Life's choline-inositol complex a couple of weeks ago. It contains only 100mg of pantothenic acid but, I think it's working already. It's helping with my sinuses. I'm not sure if it's doing anything for my hair.... I can say that most of the Country Life brand of vitamins have been very effective. I was taking 5mg of Country Life Biotin and noticed thicker roots. It didn't seem to speed up my growth though