Ecobee3… No competition… Also luv the fact it shows the wiring on your unit which you can enable or disable. For example for some weird reason, I had. W wire connected to the AC only unit which serves no purpose and ecobee3 would show heat related options too which had no purpose. Rather than physically climbing up the attic, removing the wire, or pull out the wire from the thermostat, you can simply go to the Installation settings -> wiring -> and simply disable the W. So, now the thermostat identifies it as single Stage AC only unit and shows the menu accordingly only related to cool only. Remote sensors are spot on. Detecting occupancy is kind of slow though. And yeah… I haven’t hooked it up to ST.
These remote sensors help me a lot as I live in a split level house and the temp. In the lower levels are much cooler than the bedrooms in the top floor. Now I pick the sensors for the Home mode to the ones in the top level. So, they get cooled appropriately.