I use a few Kerastase products. My favorites are from the Resistance line and the Nutritive line.
From the Resistance line I use the Volumactive products (shampoo, mousse and mask). The volumactive products leave my hair silky and shiny with body and volume. I usually use these when I roller set. I also use the Vita-Ciment which is the one of the best strengthening treatments I've ever used.
From the Nutritive line I use the Elasto-curl products (shampoo, conditioner, mask and curl cremea) and the Nutri-sculpt leave-in. I usually use these when I do a wash-and-go and they leave my hair bouncy, soft and moisturized.
My favorite Kerastase product so far is the Nutridefense mask which left my hair smoother and more moisturized than anything else I have ever tried.
While I love the way the Kerastase products make my hair look and feel, I worry about the high silicone content and whether this might dry/damage my hair over time. So when I am using Kerastase regularly I try to clarify more often and do deep treatments with a non-Kerastase moisturizing conditioner.