The Honeywell Lyric Smart Thermostat can talk with Siri through Apple HomeKit or with Alexa via the Amazon Echo, Echo Dot and Tap speakers.
It also has geofencing capabilities tied to your phone's location. When you leave home, the Lyric should automatically adjust to a more energy-efficient temperature. And when you return, it should auto-adjust back to a more comfortable setting.
The Nest Thermostat E is Google's entry-level smart thermostat. The E has (almost) all of the same features as the Nest Learning Thermostat, but has less expensive hardware components to reduce prices.