I run Zwave and love it. Advantages:

• better range and less interference in 900mhz band with meshing
• better battery life. WiFi uses up to an order of magnitude more power. Battery in Zwave devices lasts for years, with new ones being even better in this regard
• more secure as they cannot be hacked by hacking your internet or getting on your WiFi.
• more feature rich. Zwave devices tend to be geared towards more pro use and tend to have just about every feature you can imagine
• The Zwave standards body is quite strict in ensuring devices adhere to the standard so it's much harder to get "stinker" devices that don't. This is a bigger problem with zigbee for example.
• fully local. You can be 100% sure they aren't sending your data off somewhere
• Generally high quality. I've had quite good luck with pretty much all the Zwave devices I've bought. They last a long time and are reliable if your mesh is working properly (enough powered repeater nodes).