I would like to replace the current SECO 24 VAC TA2000 Heat Pump Thermostat. I want to put in a programmable thermostat as a replacement. Would like to know brand names that are a "good" replacement for the old model. Current thermostat has one line coming from the wall, then 6 wires coming from the one line. Thank you.

Honeywell or White Rodgers makes fine thermostats. Just remember you have a heat pump with I am sure some electrical resistance heat also and that means you better get a thermostat that can do those two items. Many folks post here after they have already bought there new thermostat only to find out they bought the wrong one.

I find Honeywell manuals and stats to be very user friendly.

If you program your thermostat for heat this may cause the aux' heat to come on at scheduled heat increase time and hurt your efficiency.

I will advice to get Honeywell RTH7500D or RTH6350D.
It will be compatible