I am a big believer in Harmony, CEC not so much.
We have older equipment - a non HDMI receiver, four disc players, ATV, Roku, cable box, and an HDMI switch. That makes for a lot of independent input switching on the receiver and the TV. With a Harmony, everyone in the family, including my ten year old daughter, can easily watch whatever they want. Press one button, all of the right devices power up and switch to the correct inputs, and the buttons on the Harmony are set to perform the necessary functions. All of the device remotes are in a drawer. The Harmony may be our single best piece of AV gear.
I have no personal experience with CEC, given the age of our AVR, but all the posts I see about flaky performance make me leery of that approach.