Can't beat Öhlins, but it's at the high price end. You might be able to get one cheap off eBay and the just get a bracket to mount it. I've heard a lot of good things about Scotts as well.
I would stay away from HyperPro, though, heard of several leaking and saw one do it at my last track day as well. It was on a Kawa 636 and brand new, never been used and within the first day it had leaked all the oil