The platform that an arcade controller works on may be a lead factor in your decision regarding whether or not to buy that controller.
The FightBox K1 can come in white or black as well as K2 & K10 editions that have a joystick and more buttons respectively.
The KBGM-H04 is a dual layout controller with an aluminum alloy top and acrylic bottom. You can also add an extender for your wrists.
The Leme Tech One is a Smash controller that runs on the proprietary Leme Tech One firmware, which is HayBox-based and HayBox-compatible.
The DuelPad A16 is an acrylic controller that has 16 buttons with LED support and even comes with a modern console port.
The Ruyi Box is a stickless controller with 18 face buttons curved quite interestingly as well as two analog sticks.
The button layout of the Meisterbox M from Bavaria is supposed to make it the most ergonomic fighting game controller.
Cubs made a hybrid, the Cubstraption, that has a GameCube controller on the left and half of a box controller on the right.
The ST is a primarily stickless controller that is made of inox steel, has a see-through bottom panel, and glows in different colors.