Gateron switches are some of the most popular switches for leverless controllers, and their smooth keystroke lineup is offered in a wide variety.
The Glyph is a modular all-button controller that is available in layouts for games from Smash to Street Fighter.
The RaidenBox is a mini all-button controller that is made of acrylic & nylon and is inspired by the Flatbox & Snack Box Micro.
When not making wooden accessories for tech, StepUpSFF makes stuff like the Retro Lever-less Arcade Controller (also in WASD format).
The SLM-B5 is a mini all-button controller that can beautifully produce blue, purple, green, or red light from below.
It's nice how the Bubblebox is on the smaller side of things, but it still has ample width in a way that sets it apart from competitors.
The Slimbox R5 is a thin all-buttons mini controller infused with Kailh & Gateron switches and comes with Brook or Pico PCB options.
The Leme Tech Zero uniquely runs on the pico-rectangle firmware, yet it is still compatible with the HayBox firmware if you prefer that.
BorgTech's Super Smash Bros box controller offers a variety of keycap colors as well as Kailh Speed Bronze or Gateron Silver Pro switches.