Honestly, it doesn't need to be a "Smart" watch or have a screen. If it does have a screen, touch screen is preferred. However, since it's just a shock watch, I prefer the one without a screen, but still having the heartbeat sensor and sleep functions via the app. If the app was a bit more sleek and user friendly, it would be awesome.
Something like a smart watch would have, but make it look more like a watch.