Z-Wave has been good. Fairly well adopted and used, with the only downside being that you need a hub (not really a downside). Right now, I am running Smartthings and Wink. I honestly like Wink better, but they are having some major financing troubles. Somebody will buy them, so I switched back to Smartthings last week.
My favorite has been Insteon. Kitted out my previous house with it and loved it. Sadly though, it does not integrate with a lot of the newer stuff. Because of that, that is why I went with Z-Wave for the new house. Got about 40-50 switches and dimmers, Ecobee thermostats and switches, Alexa enabled stuff, Dome leak detectors and water shut off valves, garage door opener, and Ring cameras. Works pretty well.