Ecobee3 Lite vs Ecobee4 vs Ecobee3 is a highly debatable topic and a widely discussed one. Till today, Nest has been leading the thermostat industry and took the #1 on the market.
As soon as Ecobee joined the market and released their successful Ecobee thermostats, things started changing and they gained traction pretty soon.
Today, Ecobee is the leading company that released three best-selling thermostats. The latest one being the Ecobee4 and the first one - Ecobee3 Lite.
While all of their devices are quite good, there are some serious differences that need to be noted. For instance, the Ecobee4 has a built-in Alexa support that makes the thermostat unique and stand out.
The older models are also good but depending on your needs, it's not advisable to get the latest one since you shouldn't be spending extra money.
If you think that the Ecobee3 Lite's features meet your needs, you can get it without regretting that the newer models had some extra features.