I've tried a few 6ers. The Yamaha TRB6 is really nice, but for me, my Shuker is head and shoulders above everything else I've tried.
It's all down to personal taste of course, but if you have a custom made bass, made by someone like Jon Shuker, or Alan at ACG, you get to input all your own ideas and work with the builder to get a bass that fits you perfectly, rather than an off the shelf mass made one. That said, there's nothing at all wrong with Ibanez or Yamaha etc, far from it, I'm a big fan of both, and the Ibanez SRs are pretty light too, whereas my Shuker weighs about the same as a small car.