[jrajav]

I have long cited this one difference (the ubiquitous back button) as the tipping point that makes me consider Android feel more usable, on average, than iOS. I never considered that one reason I feel that way is because of the placement and reachability, but it makes sense. That's not the only reason, though; having "Back" handled by the OS allows a "back stack" and more seamless multitasking.