I would pick the Lumia 950, but for my dad to replace his aging Lumia 920
Why the 950
- Beautiful photos.
- Large (enough) screen while still feeling pocketable.
- Continuum support - my dad often gives talks to history groups and rather than borrowing my laptops, he could just use his phone with an adapter and mouse.
- One OS to rule them all, Windows 10 on his desktop and a fully features phone would keep things familiar and simple.
- User Replaceable battery and SD card support. Battery age has been one of his stress points.
The Lumia 950 would be the perfect phone to bring him up to modern hardware, offering just the right size to power mix he needs.