A term you may hear bandied around when people talk about what OS to choose is “mobile fragmentation.” The term itself is rather vague, but it’s still a serious concern nonetheless. Essentially, mobile fragmentation is the paradigm that mobile OSs have been slipping into in which a userbase has different versions of the operating system, meaning one cannot safely take advantage of newer opportunities if coding for clients on older systems is a consideration. In short, it’s one of the most annoying problems you’ll face as a developer.