So the results are in, and I was kinda impressed with all of the devices. My baseline device is the Extech 445715-NIST Hygro-Thermometer with Nist. Certified accuracy. In short, I highly recommend calibrating all temp sensors for accurate results.
Test Setup:
Temp changes were collected and compared via googlesheets thanks to @Charles_Schwer smart app Google Sheets Logging.
Polls were forced every 15min thanks to @geko smartapp Pollster
The Data:
Note: All logged temps before line 250 are pre calibration
The Results:
Accurate with in 1degF w/o calibration:
Nest Thermostat
Fibaro 857934005188 Modern Door/Window Sensor with DS18B20
Accurate with in 1degF w/ calibration:
(Devices on this list were off as much as 5deg before calibration)
SmartThings Multi V1
SmartThings Multi V2
Aeontec Multi Gen 5
Iris Contact Sensor (3320-L)
Iris Motion Sensor ( 3326-L)
Accurate with in 3degF w/ calibration:
Iris White Security Alarm Button (3460-L)