David, I too like Ian believe in more than one backup so I have an iMazing, iTunes and iCloud Backup. I like the iCloud backup because of portability, I can effectively do it anywhere I have a good internet connection without any other devices. If on the other hand my iPhone becomes unusable for some reason then I need a program like iTunes or iMazing to erase and reinstall both an iOS and my data.
But say I was on holiday overseas, my phone is irreversibly damaged or lost, I do not have my computer with me so I go to an Apple Store, buy a new iPhone, set it up with my details, login to iCloud with my Apple ID then I can restore from my iCloud backup right there in the store. In less than an hour I can have all my contacts, Files, calendars settings and preferences including saved passwords. Just like my old phone.
There is also a considerable time difference when it come to restoring a backup online. In an Apple store I would expect to be able to restore my phone to a working duplicate of my previous device fairly quickly but if I had to restore a lot of third party apps as well as an iCloud Photo library it could take me 4-5 hrs at home.
Whereas I can do the same process at home with iMazing in an hour.