In the context of the OP (privacy concerns): Relative to Google, a smaller percentage of Apple’s revenue comes from advertising, so presumably they have less incentive to scrape all your messages. From what I can see, Google is fundamentally an advertising company, while Apple is fundamentally a software marketplace that takes a cut of every iPhone app sold. Both sell consumer hardware too, but hardware is more important to Apple than it is to Google. All these things give Apple a slight boost in the privacy arena, I think.
And specifically about phone snooping, Apple’s RCS-equivalent protocol (iMessage? I forget the technical name for it) is completely proprietary (Apple to Apple only) and was Apple’s baby that they were able to develop on their own and force upon carriers, unlike RCS that was co-developed with them — maybe this means fewer technical compromises, though I haven’t actually studied this part in depth.
On the iPhone, definitely. We were lucky that Google rushed Android out at the time it did, or the iPhone might’ve completely taken over computing and become an absolute monopoly.
On the Mac… well, I mean, software incompatibility across systems was always a thing, from the Unix days through the early DOS days to IBM PC compatibility, etc. Windows just happened to win in the home and enterprise spaces, but it’s not really meaningfully more or less open than Macs these days, as far as I can tell — they both have proprietary app stores but nobody uses either one much, and they both require code signing for apps, but both provide ways to run whatever you want if you’re willing to jump through hoops.
If Linux is the gold standard for personal computing freedom, at least macOS is closer to that front, being a UNIX (as opposed to things like Windows Subsystem for Linux) — that’s a usability concern more than a compatibility one, though. For actual Linux compatibility, Windows computers typically ship commodity x86/x64 hardware, which actual Linux can run on a lot more easily (compared to Asahi Linux on Apple Silicon, which is an uphill reverse engineering battle against Apple’s proprietary chips and undocumented drivers).
Also, Google is in the process of closing off Android more too: https://thenewstack.io/f-droid-says-googles-android-developer-verification-plan-is-an-existential-threat-to-alternative-app-stores/
IMHO: I don’t think either company is “big E” Evil, as an authoritarian government might be, but both are flawed in their own ways. Google has some defense-related activities that I, along with some of their employees, don’t approve of. I do wish Apple were more open with their hardware and software (I’d love to run macOS on standard x86 hardware, and Linux on my work Mac laptop).
Were I a moral purist, I’d probably avoid both companies — Google more than Apple, though, just because the scope of their activities (defense, AI, advertising, IAAS via Google Cloud, Google Search, Gmail, etc.) makes their international political relevance and “blast radius” far, far wider than Apple’s.
But I’m not really, so I just guilty use products from both companies 
I have a Mac and iPad and Airpods, but also an Android phone and a Windows computer and a Gmail account I use for everything. They all have their pros and cons.
But in the context of the OP, I wouldn’t trust any of these devices with my privacy. I don’t think online privacy is a real thing anymore, and if I were truly concerned about either corporate or government snooping, I think it would require staying offline and off the grid and not using any internet-connected devices or credit cards or cars, living outside of cities, covering your face as much as possible, randomizing your gait every time you walk, etc. But I don’t want to live that way.
