My earlier mobile was Nokia Lumia. It will give you a great battery backup but its operating system is not useful just beause of in multipal task it goes to hang.
It you can compromise with operating system and want only good battery then go with Nokia Lumia 1320.
But if you don’t then better options are available here. I used nokia Lumia 1320 for one year. Always it disturbed me about it operating support system.