1. Download alternate keyboards. Lets say you like bigger or smaller keys, with ios you're stuck.
2. File system access. Sometimes people with iPhones ask me, for example, they want to know how to export voice notes, being an android user I didn't believe then that they can't just go to the file, and email or bluetooth it. On iOs you actually have to connect it to iTunes, and somehow find it there somewhere. This is IMO ridiculous.
3. NFC support. Not that it is such a great thing, it's just one example of how the ignorant apple gods decided that it doesn't fit the apple image, and even though there's a market for it, won't put it in. Same goes for the notification area up until iOS7.
4. Launchers. Changes you're whole home screen to whatever shortcut layout you want.
5. Alternate anything. The OS is open for tweaking, whether you want a different dialer app, contacts, text messaging, millions of people use apps other than the default apps for everyday tasks, things no one ever dreamed of before android times.
These are just a few from the top of my head, believe me, there are many more.