The main reason why I am still using my ZR is because of the removable battery. I have 2 batteries with me, so whenever one die, I just swap over with another one, and immediately I get 100% battery power. I'm also using the charging dock (not the original Sony one), so I have a spare slot to charge my additional battery, while still charging the phone. I don't like to use powerbank because I don't really like the idea of bringing the phone with a powerbank attached to it by a cable. It's too cumbersome to me. Personal preference though. Your mileage may vary.

My workday pattern is not fixed. Sometimes I am in the office almost the entire day. Other days, I am out of the office most of the time. So I tend to keep my phone on data most of the time. I check fb & whatsapp quite often, so I would say my data usage is probably quite regular (not light, but not heavy also). I find having 2 batteries is the best combination for me. 1 battery will easily last me from 8 am till evening 6 or 7 pm on a busy day. On a more relaxed day, I won't have to change battery at all. I leave my phone on the charging dock overnight.