Hello, I want to install a programmable thermostat for cost/energy savings but not sure which one I need. Looking for some advice.

Here's what I have now, as far as I can tell..

There is no indication on the old thermostat what brand it is (just has name of the company that installed it), but I see everything else on the system is Goodman. I found some installation instructions for the air handler that have some thermostat information, but it list two different possible thermostat model#s: CHT18-60 or HPT18-60. I think I have a heat pump with emer. Heat.

Existing wiring is 6 wires:
Y - yellow
O - orange
W2 - white
G - green
R - red
E - brown

What type of thermostat do you recommend? It seems all the ones I have looked at say they are not compatible.

Based on the description you have given, it sounds like you have a 2-stage heat pump system. If this is true, you will need a 2-stage heat/1-stage cool thermostat that is compatible with heat pump systems. To maximize setback benefits with a heat pump system, choose one that offers adaptive, or "smart" recovery.