MicroPython vs CircuitPython for IoT Projects

I've been running both in production (well, hobby-production) for about a year and here is my honest take.

MicroPython is faster, has better community library coverage for older modules, and runs on a wider range of hardware including ESP32, STM32, and RP2040. CircuitPython is backed by Adafruit, which means their hardware is first-class supported and the beginner documentation is outstanding. For raw ESP32 WiFi projects I default to MicroPython because the urequests and ujson modules are more battle-tested than their CircuitPython equivalents in my experience.

For Adafruit Feather boards, RP2040-based boards, and anything involving NeoPixels or I2C sensors, CircuitPython's library ecosystem is hard to beat. The USB drive workflow (just copy files) is also genuinely nicer for rapid iteration than mpremote or Thonny.