I currently have the FiTech Go 600 system and am very happy with it.
I'm sure the MSD Atomic is a great system as its been around for approx 6 years now. The MSD Stealth I've not heard anything on.
This matrix chart may help you decide on which unit to purchase based on options and pricing.
http://image.superchevy.com/f/102114...-breakdown.jpg