I prefer iOS for a number of reasons:
1. You know what you're buying when you get an iPhone. If I buy a phone running Android, it will be made by a different company than the one that makes the OS, and then the manufacturer will modify the OS as well. So if there's a problem it's really hard to get it resolved because both can blame each other and the issue will not be fixed. Not to mention the millions of different screen sizes and OS versions that do and don't work with each individual phone model, meaning an app or feature I want may not be available for the phone I buy.
2. I don't need advanced customisation options because I buy my iPhone, turn it on and it works. For some users modding the fuck out of their phone might be a useful feature but I don't need to do that.
3. I have a MacBook Air and my iPhone and iPad integrate seamlessly with it in a number of ways.
4. The build quality of Apple products is awesome and they (in my experience) almost never encounter software or hardware issues. When they do, Apple's customer support is first class.
In the end though, the entire debate is pointless as each user will have different needs and to be honest, what does it matter what someone else likes anyway? Just buy the phone YOU want and be happy with it