I haven't done any hacking of any of my smartwatches. If that's important to you, then I don't really have any recommendations for you (and it highlights my point about different people's definition of "comparable").

I want my watch to have time/date, alarms, timers/stopwatches, the ability to read phone notifications, always-on screen, and battery life measured on the scale of weeks. Step and heartrate tracking are also nice perks that the Amazfit Bip also includes.