I have ran both and personally I like the oem better. Easier to set up and quieter.
Also sometimes you can find a good set of used oem gears real cheap.

 

May be the old addage that you get what you pay for. I can't speak of other gears but the AAM's (OEM) that I installed went in with the same shim packs to perfect pattern and pinion depth and are completely quite. I haven't broken them yet and putting 500+ through them.

 

I was thinking of geting 3.73's or 4.10's and an auburn posi all used but good condition. rebuild the posi and have bad *** gears for 200 bucks with install kit.