Gateron switches are some of the most popular switches for leverless controllers, and their smooth keystroke lineup is offered in a wide variety.
You can choose the color of the small & light KBGM-H06M, which also features LED for its buttons and midsection.
The KBGM-H08 has Sanwa parts, and it allows you to pick the colors of its joystick, buttons, top, and bottom.
The Reversal is not just another Flatbox-based controller. It's buttons are angled in a way that should give you wrists an ergonomic slant.
Perhaps the most unique feature of the Cross Cut is a screen in the middle, which is uncommon for rectangle controllers.
The Schism is an ergonomic Super Smash Bros controller that can be folded after you are done with a session.
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.
It seems that DOIO took its creative liberties with the spacing of the KBGM-H03's buttons, especially the uppermost button.