Having worked in car audio for almost 5 years, I really must say you get what you pay for. If you don't care about having space for gauges under the radio, then definitely go double DIN. Way more reliable and fairly easy to make a fake radio face to deter thieves. Only stick with quality brands like Alpine, Kenwood, Pioneer, Eclipse etc.
I have a Kenwood DNX8120 in my Protege and love it. Especially because of the Garmin based nav and clean 5V signal outputs