Hm, your selection is getting smaller then. HTC, Nokia and Sony all tend toward phones without changeable batteries.
Practically only Samsung left among the top tier manufacturers who still let you open up the device yourself to get to the battery.
Well that depends on the model. But a battery should last several years. One of my first mobile phones which I used for many years never needed it's battery changed. And I bet I could plug it in today and the battery would still be fine.
Yeah, I just said his selection is getting smaller if he makes a changeable battery the deciding factor.
I myself use an HTC One and One X for work at the moment. Both with permanently installed batteries and am quite happy with their performances.
Take those over Apple and Samsung any day.