Shimano SLX M662 9 Speed Rear Deraileur
New SLX, Tough, Aggressive and Light, for a modern mountain bike group. Deore LX, has been functionally re-designed into two groups: New SLX for MTB and new Deore LX for Trekking.
The SLX M662 deraileur has has a good feel, shifts well, and is easy to adjust. Being an SLX product, it is not the most durable, but overall it is a very good product. I would recommend this to anybody that doesn't want to drop $200 on a deraileur, but is looking for a solid, proven choice.