Why are iPhones so popular?

I use iPhone by myself and it's just my preferring. But I understand people using Android phones, it's just not my flavour.

I have change my Samsung galaxy S4 for an Iphone 6, and I prefers Iphone for this reasons :
convenient and fast, there are no useless things, everything is well thought out and the photos are very good qualities compared to a galaxy s4 dating from the same generation of phone.

I think iPhone always have a leg up on others.

I am using iPhone X for last few months and it seems really premium in hands and it is quite a feeling to use one. Moreover, the phone is more stable than any android devices out there and does not lag that much. I am comfortable with any Apple products because of their build quality and performance.

I think "IOS" system is high quality and screen touch is better than any other mobile. Besides, "Apple" is well-known and trusted!

had iphone for years then went android and realized im using a closed jail system where i cant do anything.. android so much freedom and better imo

Simply because Apple are the best in terms of advertising, expanding their companies, their companies is in the entire world. Not matter what, they're the most popular phone market-seller after them there is Samsung.

i have nothing to say besides graphics because it has noting more than that and hype over android.

in my opinion the difference between iphone and samsung is:
iphone: longtime processor speed is always stable
samsung: will weaken over time.

Great design of both hardware and software (iOS), ecosystem.

1- Pretty reasonably priced
2- Looks really cool
3- Lots of publicity around the iphone.