No format is any better than another for macro. What matters is which gear best enables you to see what you want and consistently delivers the goods without too much fuss.
My preferred macro system is the mamiya rb67. It is very stable, uses leaf-shuttered lenses, and features bellows focusing... all helpful for macro. If I need tilts or back focus, I will sometimes put an rb lens (or the fast rz 110/2.8!) or Nikkor 120 AMED lens on a rittreck 5x7, that is a nice, stable platform. Sometimes you really do need tilts, if you are fighting for every last micron of DOF. That plus other rear movements and back focus can be very helpful.
Another macro system that I enjoy is the mamiya 645 pro with the 80/4 macro lens, that is good fun. I like the lens so much that I sometimes use it on 35mm as well.