I get the feeling OP was more interested about people who use multiple phones and what their usage is like, not people who have a collection of phones that sit in a drawer. Well, I’m more interested in the former anyway.
I only use one phone, but since it is smaller (SE3) which I prefer when out of the house, I wish I could use a bigger phone (maybe 15 Plus) when at home. But there are certain annoyances about using two phones, especially with two different active lines, that keep me from doing so. Instead I use an iPad Mini at home as my big phone, which with Continuity mostly works well, but my main complaint is the iPad is a bit too big to carry around with me like a phone, even at home. Ideal size would be a Nexus 7, which can be comfortably held in one hand and fit into most pockets, but I would settle for a large iPhone.