What's the criteria for better?

Consistency
Price
Availability
Longevity
Product support


I'm using AE for cost and availability. But then I'm a n00b, so take it my $.02 what its worth.

The last one on my list is probably important if you're running a particular model and follow recommended setups of others (pro's). I imagine however that once you fully understand how to setup your car (specifically the diffs) you can use whatever brand you like and stick w/ it.