iPhone or Android?

Rooted android with decent OS (LineageOS personally) beats any other combination. If you don't like your OS then you just change it to the one you will. No manufacturer artificially slowing your device (hi apple), no manufacturer stopping OS updates 1 year after release (hi samsung) and no bloatware that you have to live with (hi everybody but oneplus).

Of course the above requires a bit more than being a casual user that doesn't know what android version he's even running, but it's nowhere close to being difficult with whole xda being at hand.

I find iOS much more simple actually, Android also comes with too much crap from the manufacturer

I prefer my 'stupid' phone.

Everyone kept demanding apps a few years back so had to get a smartphone, went with android, rooted it, never liked apple with all the restrictions they had starting with their imacs decades ago, I'm a customization person. Mine came with slight (although useful)bloatware but I deleted those, there's a lot of storage space or memory cards now anyways so it's not a problem either way.

Android, iPhone always seem too restrcting to me and way too expensive.

definitely iphone. it has the best OS. i can actually do all i want to do with it. and the X has the best screen i have ever seen. it's really nice to watch shows with it on the train.

it's easier to have paid apps for free or for cheap on android, so now i sit on a rather good library of paid sw for android.
that, mixed with cheaper hw prices, make me choose android over ios.
my old ios device is out of updates since years, and i don't feel compelled to renew it.

iPhone.
They put serious effort into keeping their app store free from fakes/malware/etc.
The app quality in general is better (in part because Apple users spend more money, so devs focus more on those apps)
You are guaranteed OS Updates (Android OEMs not so much)
No OEM Crapware infesting your new phone. (Touchwiz?)

But in the end it's about the ecosystem you like. Having used both I can't stand Android on an OS level, even before I get to apps and such, so I stick with apple (and after a few phones I won't lie, it would take a LOT to make me switch ecosystems).
Personally I'd love it if Windows 10 Mobile had of survived, it was a lot of fun, though apps were rare.. alas it is dead.

edit for the record I rock an iPhone 8+. No interest in the X just because it's first-gen. Before that I had a 6, before that a 4S, and before that a 3GS. My 6 and 4S still work fine, I use the latter as my MP3 Player.