@Menion: nice poll
*thumb up*
simple points which came into my mind:
- most people are right handed, but also some people are left handed. Holding the phone in the left, those people would prefer + and - (zoom) and maybe other buttons on the left I guess. I am right handed.
- button-layouts will definitely vary from person to person. Some people still need + and - for zoom (often less trained, maybe older persons, friends of button-pushing,..), some are fully happy with pinch/spread or tapping to zoom. At the end things are often customisable as the pros will appreciate extra-space and full view or prefer bottom as it's not in the way of left/right-thumb-gestures (e.g. riding bike and using one hand) and screens are often mounted portrait instead of landscape, so more space at top/bottom
- I am often tipping that fast, that I still have to have certain buttons at defined places, in best case due to my customisation/choice

simple points which came into my mind:
- most people are right handed, but also some people are left handed. Holding the phone in the left, those people would prefer + and - (zoom) and maybe other buttons on the left I guess. I am right handed.
- button-layouts will definitely vary from person to person. Some people still need + and - for zoom (often less trained, maybe older persons, friends of button-pushing,..), some are fully happy with pinch/spread or tapping to zoom. At the end things are often customisable as the pros will appreciate extra-space and full view or prefer bottom as it's not in the way of left/right-thumb-gestures (e.g. riding bike and using one hand) and screens are often mounted portrait instead of landscape, so more space at top/bottom
- I am often tipping that fast, that I still have to have certain buttons at defined places, in best case due to my customisation/choice