Well, it really depends on what you want. The Mazdaspeed SS is nice because it's the same height as stock, but shortens the throw considerably and gives the more "mechanical feel" from the metal bushings that come with the shift kit. The TWM, on the other hand is actually a shorter shifter, sits lower, and still gives you the mechanical feel because it has the bushings as well. However, be advised that the TWM really needs a bolt (search the iammike shifter mod) under the shift cable to keep it from binding up.
Personally, I run the TWM shifter and stainless knob, with the bolt under the shift cable and I'm very happy with it. They are both top notch products, just depends on what you want, ie shorter throw same height or shorter throw lower height.