It's not so much features as it is potential, such as the ability to make your phone block all ads simply by rooting it (which is way easier than jailbreaking) and then downloading an app that can download HOSTS files from the internet and then block all ads from EVER entering your phone in any way, even on apps that you download from the Play store.
For most people, its also the fact that Android acts more like a desktop operating system, with full access to the filesystem, default programs, and the ability to configure your OS any way you wish. You just have way more control over your phone with Android than you do with iOS, and it takes minimal effort.
For non-tinkerers, its not an attractive option, but for a tinkerer like me, it is.
Even for non tinkers because it can be setup just like an iOS device. Thats the beauty.