a) Android has market share dominances (likely around 75% in Europe in 2018)
b) iOS is not made available for other companies to use
You could make arguments that iOS behaves unfairly to third party developers and end users, and there are some decent arguments to be made there, but none of them are relevant to antitrust law because a) means there is no market dominance to abuse with, and b) means there are no competitors to be abused.
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You said "Most phone makers don't [skip Google services] because customers prefer the Google services, but that's not Google's fault". I think this gets to the heart of the disconnect between your stated position, and the legal reality here (IANAL though).
If Google's services are supreme because of user choice, then Google should require no legal arm-twisting to push those services onto devices.
Instead, what has happened is that Google has over-reached with its Android services contracts (one example - if you want to use Google services on one Android phone, you can't make a second Android phone that uses your own services), and that is what the EU is tackling here.