I've been an iPhone user up to and including the iPhone 5. I then moved to Android with a Nexus 5 and then to Windows Phone - which was, IMO, the best phone OS. I loved it and would still be using it had Microsoft not effectively killed it. With the demise of Windows Phone I went back to Android and have had a Nexus 5x, Galaxy S6, S7, S7 Edge, S8, Pixel 2 and now a Galaxy S9. Technically I'm not qualified to contribute to this thread because I don't have a Note 9 - but I'm going to anyway.
I have been increasingly concerned at Google's data gathering shenanigans. Gathering data and monetising it is the company's business model. I'm less happy with that model than I have ever been and have recently moved away from as many Google services as possible - my calendar and contacts are now hosted on my NAS and I use Firefox Focus with StartPage as my search engine. However, given I am using an Android phone, Google still knows way too much about me. I figure Apple is less of a problem - of course it gathers data, but I am not the product in the way I am with Google. Add to that I have to accept that Apple offers a tremendous after-sales operation. I have an Apple Store nearby and it is good to know I can call in and get my phone sorted if there is a problem.
I will be buying an iPhone Xs on pre-order day.