I use my iPad because I can make it stand up and I don’t have to hold it. The best position for me is to lie on my side and put the iPad on an end table at eye level. My husband uses his smart phone a lot and I notice that his head and neck are in a forward position, not a more natural straight position like when you are standing up and looking straight ahead. He has been having neck and shoulder pain and I think that it is from looking at his phone for hours on end.