I have the BangleJs v2 and built a few small things for it. While I do like the hardware, only having one physical button kinda kills it for me. The software, community, and overall developer experience was pretty nice though.

I also tried Watchy, the eink, esp32 powered smartwatch. I got hardware v2 and I remember struggling a bit with firmware.

I had a Pebble back in the day and I'm currently wearing one from the new batch. It's the best combo of hardware and software in a smartwatch I've personally experienced.