I went with the Herpstat.
I have two Inkbird STC-1000 controllers that I do not use anymore. The STC-1000 is very popular, I successfully incubated and hatched using the STC-1000, and I am sure it will do a good job for you. The STC-1000 ultimately did not work out for me, tho. Two things bothered me-
1) the STC-1000 will display tenths of a degree but it can only be set in full degrees. I could not set it to 99.5 degrees, I had to choose either 99 or 100 degrees.
2) the built-in hysteresis (deadband) of one degree resulted in a cyclic temperature swing of >3.5 degrees in my old incubator, and a temperature variation of one degree too warm or too cool has been shown to affect development in chicks. Watching the temperature go up and down bothered me.
I purchased the Spyder Robotics Herpstat 1 and I am very happy with it. The Herpstat is a dual-mode proportional controller, not an ON/OFF switch with a digital display like the STC-1000. It's all or nothing with the Inkbird; full power when the circuit is energized or no power when the circuit is de-energized. The Herpstat works like the cruise control in a car, increasing or reducing power as necessary to maintain the set point (speed in a car, temperature in an incubator). I can set the Herpstat to a tenth of a degree and in my particular setup it keeps the temperature at that temperature.