What is your favorite permanent color line?

I may be moving into my own suite and i need an estimate of how much its going to cost me. Im using Redken at my current salon, but i am not impressed with the coverage and they kind of lack in variety of colors. Im looking for something that will be easy to carry in a suite with a variety of colors, guaranteed coverage, no weird unexpected shades/tones, etc. And the easier to understand, the better.