The original Pico (RP2040) is no slouch either. I use it and the Teensy for most of my experiments. It’s great if you want to turn some wires into something you can access over USB. There’s even good keyboard firmware for it that is very easy to build and configure.
I’ve also been dabbling with Daisy Seed Pod (STM32H750IB, single core 480 MHz Cortex-M7) for doing audio and synth stuff because it can have a LOT of full speed external RAM (64MB) for doing time based effects and samples or granular synthesis or running larger projects.
