I recommend a different consideration than the usual design, battery life, OSHW, etc : connectivity.

So typically you get BT but that's not enough, you need a bit more since it's not a well recognized device, unlike e.g. headphones. Typically you would need a companion app, for GrapheneOS, Android more broadly, iOS or a Linux phone. This is where GadgetBridge comes in. The goal of the project is to... bridge gadgets that are not standalone. Instead of having a myriad of (usually proprietary) apps that basically all do the same thing (pair, configure, handle notifications both ways) have 1 that does it for all such device.

From that standpoint, namely GadgetBridge support, at the moment the recommendation is Pebble (which is how the project started) or PineTime.

PS: I personally have a Pebble (with hardware issue, so not sure were), a PineTime (also hardware issue, touch on screen AFAIR) and finally a Watchy and... honestly I don't wear any anymore. I don't get enough benefit from it as typically I have a phone nearby and when I don't it means I do NOT want notifications.