Choice of technology would depends on connectivity and customization options.
- WiFi would depend on whether the vendor provides a native cloud to cloud integration with SmartThings and I don’t see any right now
- ZigBee vs ZWave depends on your choice and also feature availability. For example with the Z-Wave version you can use third party custom device handlers like this one which allows you access to advanced features like humidity, energy saver, setpoint limits, advanced configuration, filters etc (depending on what the Z-Wave module supports). ZigBee doesn’t have custom device handler as yet you’ll be using the stock ST device handler which only provides basic capabilities.
Also this device acts like a repeater when using a C-Wire. The Z-Wave module is a 700 series chipset which should give you great range and battery life and would make for a good repeater. The same would go for the ZigBee version. So it comes down to what you want. ZigBee and ZWave would depend on hub connectivity, WiFi version (if there’s an available integration would depend on cloud connectivity.