I have to imagine the takeaway from comments in this thread would be a big old "it depends." Which is the best almost certainly depends on what you are looking to optimize for and which trade-offs you are willing to accept. Is a long-time iOS user who has been casually eyeing other options, I'm curious what other folks will have to say.

You are asking for a heated debate.

I would say its pure preference at this point. Both operating systems have converged towards each other in the last few years, where nowadays it really just comes down to your taste, the ecosystem you are in (or want to be in - ), and whether you value having potentially a bit more freedom (with some devices that make it easier to flash custom ROMs/Kernels).

What should be mentioned though: Android is not anymore as tinker-friendly as it was 5 years ago, a lot of OEMs make it hard to even unlock your bootloader's, Google made it almost impossible to run anything custom (due to Play Integrity) without you losing access to half of your apps - so in practice, I feel like Android has not even anymore that specific anymore.

If you have special preferences, there might be a specific OS/Phone that can accomodate you better but that is something you'll need to know.