You have to draw the line somewhere, otherwise if you start tracing back you end up with handful of operating systems and it seems like they are all the same, while they are not, very similar but yer different, there is a reason to why one forks something and creates another branch, it's usually not just re-branding...
Yes OS X and iOS are based on the same core but there are major differences, how resources are allocated for example, multitasking is also handled differently. You can't just say that it's the same operating system, then compare OS X to android and announce iPhone as the winner...
I use iPhone for testing and developing purposes only, and my actual devices are android. Android flagships are always super powerful, latest iPhone is also always supper packed, they all excel in different fields, the user experience is also completely different, what's better than the other depends on personal needs, not just for between iPhone and android but even for which android phone do you need. There isn't just a single winner that trumps everything else... despite what apple fans believe (and samsung fans nowadays too!)
You can't go with personal favorites, you have to be more objective (Apple fans were always declaring PowerPC as superior to all pc processors, right until the moment apple switched to intel, anyone remember that?)