Let's be honest, the only reason the iPhone even sells is because of iTunes. It doesn't sell for the use of syncing between it and a Mac computer since the vast majority of people in the US own PCs. It doesn't sell for the screen size or the specs because there are larger phones out there with better specs. The only reason it sells is because too many people think itunes is the only way to get multimedia to their phones and they are heavily invested in it. The iPod got everyone tied into iTunes and the iPhone just followed right along. If it weren't for people being so attached to iTunes, iPhone with the small screen and inferior specs wouldn't even be in the top 5 selling smartphones.
The syncing is a major advantage. Syncing with Android devices is tricky and can be messy or difficult to do. Without the syncing, iOS would still have some advantages, and the only hardware disadvantage that I care about is the lack of an SD card. If everything was the same as it is now except that iOS did not have syncing, I would just not use either smartphone, but I'd take an iPhone over an Android phone.