I have three everspring st-814 z-wave temp/humidity sensors and I’ve found them to be pretty good. I’ve compared each one to a calibrated digital thermometer/hygrometer and although each was off by a degree or two, they were consistent so with a temperature offset I’ve had no problems. I think humidity isn’t as accurate but you mentioned you mostly care about temp.
They will pair with ST without any custom code, but if you use this device handler you can use the temp offset in the mobile app (the stock device handler won’t have an option for temp offset).