There are many color variations with concrete stain but one of the top choices that goes well with traditional and modern design is a brown/walnut. These are some of the top brown concrete stain products available.
A lighter brown, this is best used when applied in a mottled pattern with a darker color. Otherwise it will all be lighter brown.
This is a black acid color, but it can also be used in a diluted or mixed color state to make your other colors a little darker. Keep in mind with acid you cannot usually go over it with a second coat so this color needs to be added next to the application of a lighter color OR mixed in to alter the color. This is generally used in the mottled effect you see above applied with a
Be sure that when using acid based stains or cleaners, that you use an acid-resistant sprayer with them. Here is a good quality choice: