Sally's Beauty Supply has a good sale this month on their sulfate free shampoo. The brand name is Hairtrition and it is $7 a liter for shampoo and the conditioner. Great price and I think it does a wonderful job protecting colored hair.
Can't say because I've never used Kenra but I have found the workers at Sallys to be very helpful when I have a question. I have used that kind for over a year and I really like it. I was using Goldwell and Biolage before I found this.