RBoy
(www.rboyapps.com - Making SmartThings Easy!)
6
Perhaps another question to ask would be what brand, since reliability often is tied to the manufacturer.
I would recommend Yale or Schlage locks in the US (for Europe there are other options). The are the most reliable over Z-Wave. Kwikset locks z-wave/zigbee modules tend to give trouble after a year or so.
If you want to compare features between locks see this: