I switched from Android to iOS and haven't really looked back.
iOS isn't perfect, and there are a few things that I miss, but overall even at the time of switch, iOS just consistently feels more responsive, fluid, &c. Also, iMessage and FaceTime are great, plus integration that just works with my Macs to let me do things like handle text messaging and phone calls on my computers.
A $200 premium over the 8+ doesn't seem ridiculous at all to get a comparable screen size in a much smaller body size.
To add nuance to Nathan's point on CPUs, where Apple has a huge lead in the mobile space right now is in single-threaded performance, which essentially bottlenecks responsiveness. The Qualcomm CPUs have been competitive (and sometimes ahead, at least on paper) on multi-threaded perf, but if you've ever extensively used both iOS and Android devices, the iOS devices consistently just feel more responsive.
In a vacuum, as a mobile OS, I think Android is better because of intents, cross-app integration, &c., but iPhones are just smoother in use, plus their suite of applications is really, really, really convenient in practice if you use a Mac.