Factory stereo or full blown audiophile system? Dealer installation or after sale installation?

I've been shopping for a new car and one of the things that's very important to me (as you will all agree, I'm sure) is the quality of the sound system. But since I lease my car, I can't be bothered with installing my own rig and I just live with the factory stereo.

I was on a test drive yesterday and Images In Vogue's Can't Mistake My Lust for Love came on the radio. I haven't heard that song in years. Seemed like a good time to test the speakers. The poor salesman didn't know what hit him!

While we're on the topic of cars...does anyone have any thoughts or insights on the Ford Escape or Subaru Forrester?