Which temperature field best represents indoor living zone temperature?

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I am trying to use the difference in outdoor and indoor temperature to model for a Transactive Energy system.

I am using SITE OUTDOOR AIR DRYBULB TEMPERATURE (Environment) [F] for the ambient external air temperature.

However, I do not know whether I should use ZONE THERMOSTAT AIR TEMPERATURE, ZONE AIR TEMPERATURE, ZONE OPERATIVE TEMPERATURE, or ZONE MEAN AIR TEMPERATURE of the living zone as my representative indoor air temperature.

I have noticed that all the fields are pretty much identical except for the operative temperature, which is different by about a few deg F comparing across the same timestep.