What OS do you prefer your smartphone to run on?

[ebw]

iOS by a country mile, but admittedly I've only really used up to 6.0.x. I've been using a top-tier Android phone (4.3-4.4) for the last year, and it is an embarrassment to the species. WP might be more polished and reliable (who knows, I've used it maybe once) but needlessly obtuse.