The specs are the tell here.

Herpstat is +/- 0.9ºF
zoo med +/- 2ºF
PE2 ir gun +/- 1.7ºF
Most IR guns range between +/-2ºF to 4ºF

The herpstat in correct working order is many times the most accurate. Thermometers come in two flavours, cheap or accurate. The herpstat is quite accurate for the price there are better more accurate digital thermometers out there but few under the 200$ price point. My personal one is well over the price of the herpstat 4.