[dekhn]

I've worked with all the various Arduino and other MCU boards as well as Pis. My preferred chip is still an Arduino Nano in a screw terminal carrier (just today I wired up one to make a rotating stepper that rotated in sync with a camera trigger, to do 3D scanning for Meshroom).

I love the old Uno, it's solid as a rock but of course has very limited CPU and memory. I would only use an Uno if I had a specific shield that fit the Uno and needed 100% compatibility. The dupont connectors are too loose for permanent projets that get shaken around... it's 5V, which makes working with some hardware easier (although most things "kinda work" with 3.3v MCUs, some stuff doesn't).

The Nano is like the UNO but smaller, although you can get nice little screw terminal carriers that make permanent connections more reliable.

The Teensy is a faster arduino with some very good support libraries. It Just Works, most of the time. But I haven't ended up using it for anything; I've replaced it with Nanos or ESP8266 or ESP32.

The ESP2866 and ESP32 are great systems, truly amazing what they can do even if they're just emulating an Arduino. however, there is a fair amount of compatibility problems with the 32 (for example, I have a sketch for a self-balancing robot, it works fine on Nano and ESP2866, but hangs on the '32). But the 32 has a special trick up its sleeve: the arduino functionality is really just an emulator that runs inside an RTOS. I started to play with FreeRTOS on ESP32 (https://docs.espressif.com/projects/esp-idf/en/latest/esp32/...) and was really impressed. It feels a lot like my days using a 286- no virtual memory, a few megs of RAM, and basic networking.