Best temperature compensation equation?
Open loop temperature correction techniques are very challenging as they have to account for both static errors and dynamic temporal effects. The dynamic temporal effects refer to the thermal memory in your device under test and its interaction with the environment such that there will be response time involved from any change in the environment or its own self heating, and that response could be of multiple order.
If open loop is necessary then the static effects are best compensated with an actual measurement from the sense thermistor (with intent to compensate for any offset from that  measurement point from nominal). The dynamic effects can be best compensated with similar dynamic characterization to determine the dominant poles and create the compensator from that- the characterization can be done by sweeping a thermal sine wave (or ramp but that is mathematically more complicated) in a thermally controlled chamber starting with a very low frequency oscillation (cycle time over many minutes or more) to find the point where the output phase has shifted 45 degrees from the input (first pole) and then continue to 135 degrees to find the second pole (typically a thermal system will consist of very low frequency poles). Using a two pole open loop compensator should significantly improve an otherwise static solution.  This would be necessary if the temperature is still desired to be controlled, although open loop. If not then the direct measurement could be made and the error of the result vs temperature can be corrected from other characterization measurements- for this it is critical that the thermistor is thermally intimate with the temperature sensitive component with no additional thermal time constants in between- otherwise significant 3d finite element analysis modeling of the path between the core sensitive area and the closest measurement point may be required to resolve these same questions.
When temperature compensation is critical, a closed loop solution can be much more practical and will provide the best result, if you can spare the additional cost and power to temperature stabilize the device. For this, small ovens (a power FET or resistor can be used as a heat source) can be used when the device temperature can be maintained above the otherwise maximum temperature due to environment and self-heating, or when lower temperatures are desired, small thermo-electric coolers can be put to use. Finally where possible further insulation from the environment to make the heating or cooling most efficient can also be employed. A temperature sensor on the device combined with a PID controller makes for a highly effective solution in minimizing any temperature effects.