My platforms are PC with Windows 10 (+Chrome browser inside) and Android phone.
I need to read a large PDF (with formatted text, not just images) switching between my PC and android, and I need to make notes and sync them. I don't need reflow.
I usually use Kindle on Android for most of the Kindle books reading (and Kindle on Windows 10 very infrequently), but as far as I understand, it can be used to read PDF, but there will be no sync. I might be wrong here.
I have tried Google Play Books just now, it allows to upload my PDF, and it syncs reading position and bookmarks. But Google Play Books converts PDF to images before it will let me read, text becomes somewhat blurry, and I cannot enter notes - to enter notes in Google Play Books you need to select some text first, and there is no text to select in Google Play Books version. So far it is the best I could find in terms of sync (bookmarks still work), but the text is quite poor.