I haven't tried Viviscal, but I've always heard wonderful things about it. I am currently taking Nioxin Recharging Complex and am on my third bottle. This has been combined with the MN/NEO mixed in with Lenzi's Request. My hair is currently in twists and all I can say is that my edges have grown in FULL and THICK - this was an area of concern for me. In terms of length, all I can say is WOW!! I have my hair in the Afro Kinky Twists and the growth has been outstanding!! I plan to take them out in July, at which time I should be able to see just how much my hair has grown. But I can tell by the way some of my twists are hanging..that it has grown tremendously!!
I first started out using the Lenzi's Request. From March 11 to April 11, I gained 1.5 inches. After April 11th, I added MN and Neo to my Lenzi's Request and my hair took the f*** off!!! From that point, I added the Nioxin (2x's a day) and I could just see my edges filling in, my hair growing underneath my twists, my eyebrows, eyelashes, etc.
I've tried HF 37 and while they were effective, I do not believe that they were as effective as Nioxin. HF37 was far too expensive.
Besides, Nioxin not only helps with one's hair, but skin and nails as well. My skin is flawless and my nails are long, strong and beautiful.