No neutral required will be a difficult requirement. Generally, the only switches that I’m aware of that don’t require a neutral wire are dimmers (the switch has to power itself, and dimmers just steal a little bit of power slowly, too little to actually result in the lights coming on. This may be a problem for LED lights, which don’t require much current at all to turn on.
A neutral wire allows the switch to take the current form the line (generally black), and send it back the neutral (generally white), rather than having to send it forward around the circuit to the light. Without a complete circuit, there is no power for the switch to be listening to zwave/wifi.
If you do have a neutral wire, there are lots of options. the inovelli LZW30 is a well-priced option, but it is only in the 2.5 and later zwave binding - meaning that you will need either to manually install this binding, or wait for the stable openhab 2.5 to be released. Zooz also puts out reasonably-priced z-wave switches. If you’re going with z-wave, make sure you are getting the correct one for your region (different world regions use different frequencies).
You mention the LZW31 - this is a dimmer switch, not an on-off switch. The dimmers are still only part-way through shipping pre-orders, while the on-off (LZW30) are shipping to the public. So far the LZW30’s have been solid for me. I suppose if you know you don’t have a neutral wire, you could use the dimmer LZW31, just as either on or off (0 or 100 via openhab, or short presses on the switch). You may run into problems, though, if you press and hold the switch, which would normally start the fading process either up or down.