The Slab Mini All Button Controller is a sandwich acrylic case controller with hot swappable sockets and LED.
The CLBox is a leverless controller available in different variants and was designed to be easily upgradeable with minimal effort.
After one takes a look at the Sunga G5, the Victrix inspiration becomes immediately clear, and it is up to you to decide which one to buy.
The Superslab Digital Combat Controller is a smaller LED controller by Prong for Super Smash Bros players.
The Pinebox is a stickless controller that is made of pinewood and is also available in a Super Smash Bros layout.
The Stress Pocket Arcade Fight Pad is a mini WASD controller with unusual angles that may appeal to you more than the usual layout.
The RTU-A4 is a fantastic variant of the RTU for those who would like more wrist resting space, lap play comfort, and so on.
The RTU is a slim 1" mini hitbox with Cherry MX or Glorious Pandas switches that you can customize the button colors of.