Default [Q] Governor and schedulers

Hello users and developers...
I've been searching through changing the governors and schedulers...
What is your opinion on which ones are the best for battery life?

Also what about undervolting?
Is it safe? What about pros and cons ?
Device : Xperia Z1 C6903
Stock ROM .108 Firmware Android 4.4.4

Device : Xperia SP C5303 - DEAD
Custom ROM : Stock .266 Firmware Android 4.3
Bootloader : Locked

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