I think most people would say that it runs in tiers. My personal list, after spending some time on these forums and a few other places, are like this:
Filco
Leopold
Ducky (Shine II)
Then
Keycool 87
CM Quickfire Rapid
Plum 87
Those are, in my opinion, the most common and probably most worthwhile tenkeyless. I could be wrong though. Other brands that have some clout are HPE and Noppoo, and I'm sure more Asian brands I can't remember.
WASD is coming out with a tenkeyless sometime in the next few months, and that should be a very good keyboard.