The most popular vitamin for hair skin and nail grow is Biotin. Gelatin, Hyaluronic Acid and L Methionine are also proven supplements. You would be surprised to know how many vitamin companies are actually owned by one conglomerate that sells the same vitamins under different labels and prices. So, unless you know the distributor and producer there is no great difference in quality. I use Vitamin World because its convenient for me, and i have no complaints.