if u are looking for low battery drain then stay away from custom roms especially cm based roms.
not only they drain the battery fast because they are badly ported or whatever but also they are missing samsungs energy saver mode which does save alot of battery. (only enable cpu and u will never notice its on)
so if u really want to use a custom rom then atleast get a tw rom.
my best experience for best battery on my s2, s4 and note 3 is original stock rom with bloatware removed, energy saver mode on (cpu only) and xposed+xblast module.
that way i got best battery on my s4 (almost 6 hours on screen time or 3 days standby time), all tw features and all features i want from a custom rom.
also on every android phone in my house i had a battery drain while having wlan on in standby mode.
i noticed this not when having the screen on... only like at night when the screen was off.
this took me about 1 day standby time... so ihad only 2 days standby and not like now 3 days.
lost like 10-15% every night while doing nothing. now its 1-2% every night.
this wasn't the fault of any apps installed or anything else. only thing which help me with this was buying a new router.
after researching which one would help me with this problem i decided to buy this one. cheap and also very good and alot of settings.
other then that NEVER use geenify or any other battery tools. they will not help at all...
only app that could help is betterbatterystats.