Zwave or Lutron Caseta

My opinion: if you say you've never had problems with Z-Wave switches before, then there's no reason to switch to Caséta. However, Lutron products do have a reputation for high reliability, though usually also a price to go along with it. Either can work well, but Z-Wave will work without another device (the Lutron Smart Bridge Pro), and if you have other Z-Wave devices, they will also act as repeaters and strengthen your mesh--something you might want to consider if you do replace any. (If you have a ton, it's also more or less possible to have too many Z-Wave repeaters, or at least too many poorly placed--not that you can control where switches are much--so you may actually want to consider something else then; but this probably isn't an issue for most people.)