I use this
Clairol.com: Perfect 10, High Gloss Hair Color
It's only ten minutes it covers all the grays and leaves my hair soft and shiny.
FYI: I have done an experiment with the conditioner that comes with haircolor (many brands over the years) and I have discovered that the hair color fades faster when I use the weekly conditioner they put in the box. So now I use it once right away after the initial coloring and that's it. My color lasts two to three weeks longer.
Also if you only wash your hair every other day and just rinse well and condition on alternating days your color will last longer.