If you are like the rest of us, you walk past that old fixture on the wall and contemplate changing it out for one of the new smart technology products, but don't know where to begin. You head off to your local hardware store, such as Ace, Lowe's or Home Depot and stand starry eyed looking at the thermostat display.
The Center for REALTOR Technology recently reviewed Smart Thermostats and below is a handy chart to assist you with your purchase. Depending on your smart phone, be it an Apple product or Droid, you may choose a Nest over a Zen or if you prefer a battery powered over electrical hookup, a Lyric over a Ecobee3.
For a pdf version of the of study click here. 
Source: Center for REALTOR Technology Version 2