I have tried several Z-Wave temperature/humidity sensors. If accuracy is important, such as in a wine cellar, the best that I have found is the PAT02-B. It's made by Philio but sold under several different brand names--Philio, Zipato, and Safe Grow are ones that I know of.
I have 3 of them, purchased at different times from different vendors. In a controlled environment all 3 register within 2%RH of each other. Temperature within 0.2°F. That's pretty good in my book. Your mileage may vary of course.
They are a bit difficult to find sometimes. Amazon sometimes has them, but they've been on backorder there for a while. You see some on eBay from time to time as well, but you have to confirm that the frequency is appropriate to your country.