An alternative to the Tetrapad is the soundmachines LS1, which is a single touch slider in 4HP. Advantage over Tetrapad (aside from size) is the recording ability. You can record your gestures and play them back. In 16HP they also have the LP1, which is an XYZ controller (not sure how the Z works). People seem to love these modules!
More about control rate modules here:
Personally, I’m using monome modules with the grid and arc.