UAP-AC-HD mounting best practice/help

hello folks,

looking for suggestions on where to mount my access point it's a UAP-AC-PRO I was thinking of mounting it on a wall in my hallway but I'm not sure if that is the best location for signal or should it be mounted to the ceiling which is better ? I was thinking the hallway because it's halfway between the family room and the bedrooms but also keeping in mind I have a split foyer home and I have a second floor which is where the family room and the bedrooms are located . I am more concerned about signal on that floor than the basement because that's where we use the wireless the most. if I need to I can get another one to put in the basement if needed because I do you have wiring going to the basement. so with all that said is mounting the access point in the hallway a bad idea or a good idea that would be halfway in the middle of the second floor