I like iOS, but not Android. Let me explain why.
I personally love Linux, Unix philosophy (I'm even sometimes an old beardy zealot about POSIX standards and the old way), and inherent customization possibilities.
On the other hand, I don't want to manage my phone like a desktop or laptop computer, or a server because of a plethora of reasons. First, user interface is not very suitable for that. Second, there's a lot more finicky things to manage. Last but not the least, that management task is continuous.
iOS takes all of these away. Complete backups are built-in (I know android has it, but I don't know how bulletproof is this). Defaults are sensible. Settings do not change spontaneously. OS behavior doesn't change drastically from device to device (Every android vendor tunes their OS and background process policy differently, creating a lot of WTH moments and more finicky management tasks). Updates are not slowed down by the vendor, the operator, the distributor and today's weather.
While iOS is a pretty strict walled garden, devices are set-up and forget. Even you forget that you have an iOS device, because you use it without thinking.
Radio security, isolation and its reasonable and unreasonable parts are discussed here extensively. As a HAM radio operator, I can only say that, radios can do wreak a lot of havoc even with informed tinkering, without any bad intentions. If you take a relatively cheap SDR and listen to your neighborhood spectrum (just see the traffic, not decode anything) your jaw will drop. It's a very crowded up there, and there's a lot of non-public traffic.
Another stuff about custom ROMs and Stock ROMs is SIM services. Yes, many of the SIM menus just sit here unused, but there are useful ones like mobile e-signatures. I carry my e-sig with my phone, in my SIM. So using it requires a verified and official software stack. As far as my experience goes, no custom ROMs run these services (intentionally or unintentionally).
I manage my family's Android phones, and I personally use an iPhone. As far as I can see, it's much easier to leave an iOS device on its terms and it'll fare better.
Feel free to discuss, counter or just burn this comment down. :)