Reasons I prefer the phones that use the Android operating system:
(1) Having a battery that I can take out. I can replace it if it wears out, carry extras if needed etc. Most Android phones do not have an embedded battery.
(2) I don't have to use Apple's proprietary charging cord. Most Android phones use the common micro USB type cord. I read that I-phones sold overseas use the common USB connection, Apple is just taking advantage of it's customers here is the U.S. by making them use a non-standard charging cable.
For me it comes down to having more options with the Android phones.