Not sure why, but after going to 4.4.2 my battery life sucks. Nothing helps. I have greenify, AppOps, disable service, and my phone sleeps like a baby. I then turned auto brightness off and my phone battery is back to normal. I can actually go a full day without having to run for a charger now. My screen on time went from 3 hours to 4 hours. My Android OS and And Kernel(OS) went down a lot too.
To fix the issue with brightness, I downloaded Lux AutoBrightness. But only use the "Adjust On Wake" option. It will only adjust brightness once, when you turn the screen on, rather than constantly accessing the ambient light sensor.
Note that I have a GPE HTC One. Folks on Sense may have varying results.