In general the best part of the Pi is that it's so stable as a platform. Everyone has the same hardware and generally the same OS so guides online just work - it may be one of the if not the best Linux on the desktop experience I've used personally.

Along with that the gpio is there and ample so it's extremely easy to just start using it.

I do argue an esp 8266 or esp32 are better for a development microcontroller but you have to muck with cabling it up before you can even load a program on it which is a few more extra steps than a Pi