I think that the 5X would be best because it seems to be more sturdy when it comes to how often we drop our phones! Right now he's using some old ZTE that the screen is trashed because I messed up his LG!
I would like to have Nexus 6P, because I purchase it last month and someone stole my Nexus 6P just after 2 days of receiving it on my brother's wedding night.