I have moved your post to this topic. If you read the instructions in the first post of the topic you originally posted in, you will see that it is intended for nominations only and not discussion, with discussion being linked to for here instead:
As for the actual question, many contact sensors these days have a built-in temperature sensor. This includes some of the nominated products, including at least the Iris and Xfinity models. But I also haven't heard of problems with the ST sensor on the C-8. You may want to make a separate topic about your particular problems, since if you're dealing with a larger Zigbee network problem, it may come back regardless of what contact sensor you use.
Beyond some mentioned there, the Centralite 3323-G (3-series door/window sensor) does temperature and is made by the same OEM as the (nominated) Iris v2 sensor that has long been discontinued. I might also suggest the current-generation SmartThings Multipurpose Sensor, but it normally costs more and doesn't sound like you'd use any of the other features it offers.
