For the past year, I used Google for mail/calendars/contacts, and iCloud for notes/safari/documents/find my x. This somewhat worked. A handful of my contacts kept getting duplicated (to something on the order of 100 instances). I got fed up with this behavior last week and migrated contacts over to iCloud. So Google gets mail and calendars. I'll see how it works out, but based on this past week, I'll continue to run with this setup for some time to come.
FWIW I have an iPhone. But some of the contact behavior was *very* strange. Like a long time phone contact loses the phone number then gets duplicated 100x. Or half of my new contacts being renamed after I've added them on my phone. For example I add a contact on my phone with the last name is put in as "Smith (medicine intern)", which Google later renames to middle: "Smith (medicine" Last: "intern)"