5" really is the absolute maximum, and already bigger than I'd hope for. Small hands, want something I can actually use one-handed.
Something like the 2013 Moto G would be absolutely ideal (shit, it's been 2 years since that phone came out?). For me, 720p is fine, especially on a smaller screen. Maybe the 2015 version would be fine, but I really don't trust them to update the thing anymore.
As for the HTC A9, I actually think it looks really nice - but it's far more expensive in Europe than it is in America.