I switched to iPhone because the OnePlus brand-enhancements was the “last straw” of my experience with devices in the Android ecosystem. Other problems:

• Updates. Major operating system updates maybe only lasted about a year. With OnePlus I think they even tell you that you’ll get two major updates and after that, the “device” is practically “end of life” if you wanted to avoid security issues.
• UX jank. Even if you had infinite major Android updates, Android itself was perpetually moving goal posts with how applications “looked.” This was most prominent when you tried to assist someone with a different (older or newer) version of Android. “Where things were supposed to be” for settings etc was always different between versions. If you asked them which application they were using for a function, you invariably got a “blank stare” because they did not in fact know because they were using the default…
• Shovelware. Every phone came with uninstallable applications which were nearly always crap, but somehow essential and were configured to be the default for messages, calling, contacts, etc.

I’m not going to say that iPhone does not also have these kinds of issues, but combinatorially iPhone has less of them because you are not multiplying configurations with different screen resolutions, microprocessors, Android versions, manufacturers, carriers and promotional rate plans. I won’t buy locked devices, because for me, it is better to consider the mobile phone as a tool you buy, and not a flavor-of-the-season vessel for a carrier’s service plan. The prices of unlocked devices are closer to the true value of the device.

OnePlus was wonderful, it was just the kind of support (helpfully and covertly making apps slow down to increase battery life) that I needed to switch to Apple iPhone.