I use L'Oreal Excellence and found that it doesn't damage my hair. Then again I'll use a silicone conditioner (Feria conditioner with amodimethicone) right afterwards and that might help. It's an easy cone to wash out if you're CG, but might help in retaining the color and conditioning the hair, at least short-term. I don't use the conditioner in the box as it has protein and makes my hair frizz like there's no tomorrow.
However, I'm finding that it's not taking care of all of the gray. I use a hair mascara from Sally's to temporily cover the gray (and roots) in between coloring and that helps some, but I would like to find something better as well.
It seems that some grays are just too stubborn to be colored. It seems from the posts I'm reading that people have had varying successes with a whole variety of different brands.
I'm going to continue with L'Oreal Excellence but leave it on a little longer each time and continue with my hair mascara.
That's right, I said it! I wear scrunchies!!
I am a sulfate washing, cone slabbing, curly lovin' s.o.b. The CG police haven't caught me yet.