I was looking on Thule and yakima. They look pretty solidI've got a Thule. I would just as happily have purchased a Yakima, but I already owned a whole bunch of Thule attachments from when I had my Thule-built Mazda P5 rack.
Either of the main two brands will work great, last you forever, and offer tons of flexibility from an attachment POV. None of the other brands even comes close in terms of fit, security or quality.