I prefer iOS due to how optimized it is to run applications, the first-party, unfragmented developer support, as well as the more unified ecosystem with other products like Apple Watch, MacBook, and AirPods.
I use an iPhone 8 Plus and it just recenyly got iOS 1.13.3, the lastest iOS software build. I love having the most up-to-date software.'
Conversely, I like Android devices mainly for the hardware. Samsung and OnePlus' hardware are unbeatable, waterproofing, high-resolution screens, awesome cameras, and decent pricing compared to Apple's products...
The one thing holds back Android for me is the lack of software support, it took 9 months for my Samsung S8 to get Android 10. I absolutely loved the S8's 2960x1440p SAMOLED screen, it was amazing. Couple that with the exceptional camera.