So, i will list the pros and cons of both operating systems. I will try my best to be unbiased.
Android
Pros: Yes, it is way cheaper. Also, android is a lot more customizable than iPhones. That's one of the biggest factors to it, customization. Another thing is variety. There's only an iPhone for ios, but in android, you have the htc m9, sony xperia z3, lg g4, etc. So that's another thing, Maybe you like one android design over the other, then you have some choices you can make. For windows people, android runs off of linux, which is the same as what windows is built off of. So you can find similar features, such as moving files from folder to folder, downloading content straight off of your phone browser and installing the app (such as root apps, get them on the web, and install). So there is also a bit of convenience, vs ios, where you have to download off of a computer, hook your phone to the pc, and go through a series of steps on your pc to get the app onto your apple device.
Cons: Not as smooth or user friendly as ios. Maybe if google focused more on android than trying to overtake facebook with their stupid google plus crap... You get what i mean.
IOS
Pros: It is a lot more developed so it will be a lot more smoother and a very very tiny nanosecond faster. It is also very user friendly. You don't have to worry about random screen rbg settings, random folders such as com.android.(insert something here), etc. It's just a lot more simpler to use. Also, it is more secure than android since apple's ios is very locked down. So you don't have to worry about getting hacked (Basically, The chances of you iphone being successfully hacked are lower than an android's chance of getting successfully hacked.
Cons: No customizations, what-so-ever, besides background. Hard for me to use, i need my back and menu buttons (haha). Hella expensive.
Those are the reasons, if people even see this, but yeah. It's down to what you prefer. Do you like more control and more customizations? or do you like security and a user friendly ui?