IOS 12 can be installed on the 5S, which is the oldest 64 bit phone. It was launched in 2013.
My kid has it on a 6, and it's legitimately good performance there.
Good luck getting the latest Android onto a 5 year old handset without jumping through some non-trivial hoops.
[1]: http://www.iphonehacks.com/2018/09/ios-12-performance-improv...
I also have an iPhone 8, this is an Ok phone but is a worse experience than the 4 year old Android phone. Despite the cost being much higher, the screen is worse quality, for instance.
My partner has a 6 and it is remarkably slower than both. To the point where you sometimes just want to give up on whatever you were trying to do while waiting for a map or Spotify to load.
Maybe your experience is different to ours, but I'm only reporting what I see from using all 3.
You're lying. Installing a custom third-party Android ROM is way more than a 10 minute process, your OnePlus X is barely more than 3 years old, and there's a huge difference between a random OS image you downloaded from a forum online and manufacturer-supported OS updates for a 5 year old phone.
iPhone 8 vs Nexus 6 from 2014, back when Google marketed that series as reasonable Dev devices, not necessarily flagships.
326 ppi vs 493 ppi
750 x 1334 pixels vs 1440 x 2560 pixels
IPS LCD vs AMOLED
Somewhere there is a tongue in cheek meme comparing a sister phone, the Nexus 4, from 2012 against a 2016(?) iPhone and it's quite interesting how many features the Android phones had and were mildly credited for that when copied to iPhone were /world changers!!1/
Granted, Android phone manufacturers have wised up and besides things like the Nokia 6.1 you can't really get a good mid-range Android phone any more... it's mostly clustered around either the humble Moto E or the Note 9 price points.
Spoken like someone who's never actually used a 5 or 6 running iOS 12.
Also have an 8, which admittedly is an ok phone if horrendously overpriced but work paid for it so I can't complain.
Yeah... Good luck running the latest version of iOS on an older iPhone. (Many are still have a 5/6 and you really don't want to update those if you value a reasonable experience and latency.)