Nothing beats reliability than a factory stock suspension system. They where built and garanteed to last a good while. This is not your typical Model A suspension setup anymore.
The factory spent millions of dollars during the years to come up with a good compromise between good handling, reliable and costs efficient parts, all with safety in mind.
Most people who say the aftermarket stuff is better are usually comparing their fully neglected and worn out stock suspension to a brand new aftermarket setup with all new parts. No wonder the new stuff 'shines'.
Also since they just spent a small fortune on the aftermarket stuff, they won't be very inclined to say the difference is minimal.
If they where to properly fix up the worn stuff on their suspension, and do some more on focussing and part-upgrades on handling, the difference will be much smaller.
The factory Mopar suspension is a well proven system. Read up on the various roadtests the car magazines did in the '60s. Most Mopars outhandled the stuff that GM and Ford had to offer.
