With a Stumpjumper, you must be doing XC not FR or DH right? So with RockShox, I will go with SID. Its light (3lbs) for the cheapest one.

Marzocchi Marathon XC or ETA is good

RockShox Reba is ok if you don't mind the weight but U turn don't last long based on old RochShox experances

Or if you don't mind the weight, Manitou Minute for $399 at www.pricepoint.com

Fox Float RLC,Talas RLC, FX Terrlogic is also good.