For my LG G2 phone the Cell Data is the worst offender (unless I start watching videos or playing games). I was on vacation out of the country over Christmas and left the data roaming off. The phone went from ~ 1 day to ~4 days with wifi on syncing Mail/ twitter/ whatsapp etc. 3G/4G/LTE are really heavy on the phone battery as they use a lot of power to talk to the tower on a lot of channels at the same time.