What keeps me on Android? Mostly the fact that I have zero need to switch off. I don't have a ton of purchased apps anchoring my on Android, so that's not much of a pull. But I have all the apps I need... and I have a lot of data stuffed into my Google account... music, years of gathered and tabulated data, etc...
Google Now has become an integral part of my life, from looking out for my commute, keeping track of my bills, appointments, etc. Now iOS does have a lot of that functionality, but Google's stuff runs best on, well, Google's stuff. And Apple has iOS so locked down that I would lose a lot of the personalized awareness that I enjoy.
So really, I can't think of any compelling argument for me to even consider switching. The software, the ecosystem, the devices... I'm sorry, as a whole, Android and Google are superior.