Lavell
CEG'er
Any aftermarket brand is good. In my opinion, they all sound the same. The main difference between one brand and another is the features that comes with the head unit. The key to getting a good head unit is finding one with the features that will suit your needs. That's why I gave you the link to the Crutchfield website. They have a large selection of head units as well as a list of features for each one. It's an excellent tool to use when shopping for the right head unit.
What are the good brands? Clarion, Panasonic, Sony, Pioneer.. ?