Okay, here are my thoughts on all this.
Google has a culture based on creating new things. I've read in some places that Google employees get pats on the back and maybe even promotions based on working on new things. That's probably why a new messaging app comes out every few years, and they're even making a new operating system, fuchsia. This means that working on TalkBack, BrailleBack, and older accessibility functions of Android isn't profitable for the accessibility team, so what do they do? They work on some live captioning stuff for deaf people, which of course is great, but my gosh isn't it easier to give blind people access to the virtual world than to give deaf people access to the infinitely more variant real world? Don't misunderstand me, it's great that they're considering people with other disabilities, but they should consider us all equally, not just one at the expense of another. So that's one reason why I will not use Android, theirs is a culture of "new," not of making what is there even better. Also, their treatment of developers is awful, just ask stereomatch, the developer of Amazing MP3 Recorder. Google has begun banning not just the one developer for any infractions, but banning others by association. Also, in a later version of Android, Q probably, developers won't be able to access the whole file system of storage. What was that about Android being free as in freedom again? Google has been steadily limiting developers' power, because of course Google Drive is the answer to everything... right? right? Isn't it?
Another thing, braille. Google obviously doesn't care that much about braille. Who even owns one of those braille adapter writer digital things anyway? Who would rather read with their fingers rather than listen to the sexy rigid tones of Google TTS stripped down to its 7 Megabyte nakedness? Oh and Eloquence, we have Eloquence on Android! *drool*. In all seriousness though, what happened to accessibility for everyone? Why is it that braille can't be a first-class citizen (this really applies to any operating system, as none of them do it exceptionally well) on Android? Why is it that one cannot turn off speech when using BrailleBack? Furthermore, why is it that BrailleBack isn't included in Android Accessibility Suite, and Select To Speak was? Why are the commands on a braille display so different than on any other system?
Now, on to the third party offerings. Why can't Commentary use multi-finger gestures? Samsung's Voice Assistant can. I don't need hundreds of audio themes, I need a screen reader on which I can be productive in all that I do: reading email, browsing the web, reading books, writing and editing documents with only the touch screen (which I can do on the iPhone fairly well), and playing games. I feel like Commentary is trying to tackle so much, but is still based on the sorry excuse that is TalkBack.
And Android users may say "Well, Android doesn't need to be a PC-like operating system." Why not? Modern smart phones *are* computers! Yes they use touch screens instead of mice and keyboards, but that's input. There is absolutely no reason why a "mobile" screen reader can't be as powerful, or even more so, than a "computer" screen reader. There is no reason why a "mobile" screen reader can't make one as efficient in productivity as a "computer" screen reader. That's another reason why I will not use Android, users don't use it to its potential, so developers feel that they can keep TalkBack as a toy screen reader. Even Victor Tsaran, developer of TalkBack, uses a Mac and iPhone, seemingly most of the time. Why? Probably because he can be productive on those platforms, and just answer calls on the Android, do texting on messages.android.com or whatever the site is where people can text using their Android phone, basically using the phone as just a conduit for his other devices, not as a device itself, and I'm willing to bet that that's what most blind people do; see Jack telnetting into his phone for texting. This isn't to say that this practice is inharrently bad, it can work out, but gosh its such a waste of a perfectly good opportunity to use a phone as sighted people do. Do you see sighted people having an actual need for a computer for most things? No. Why? Because they're perfectly productive on phones and iPads. They don't need to wear a keyboard to be quick typists, they don't need to do something as technical as telnet into their phone to type. They don't even need to download a third-party email program because Gmail just isn't all that great for us. Then again, many of them that I know use iPhones, but are happily productive with them, too.
So, why iPhones? First, Apple has limited developers from the beginning, so most of them know what to expect. Actually, iOS has been opened up more and more over the years. Developers can create keyboards, Siri implements, iMessage apps, and for us, rotor options to be changed or navigate with; see Outlook for iOS for an example of this. Is it perfect? No. We don't have Eloquence, and apps have to implement voices pretty much in each app they want them in. But gosh it could be worse. Braille is pretty darn good. We have braille screen input, which, while not being perfect, does allow us to type very quickly. Other languages, like German braille where capitalization isn't used much, does suffer from English rules on capitalization, but English braille works well.
Also, iOS doesn't have Dolby Atmos for Headphones. I use Windows, with Windows Sonic for Headphones, for all that though. iOS doesn't have an Esperanto voice. Neither does Android by default.