If ease of use is important, the Canon.
Looks that way if you're used to Canon. If not, it might look different.
Of the three, the Canon is the one designed for ease of use.
Is there anything substantive to back up that statement? Surely, they omitted some of the 'original' UI features on the R that didn't seem to work out great, but I'm sure that the designers at Nikon and Sony also had ease of use in mind when they designed their cameras. Whether they hit the mark is a different matter.
Lets compare controls.
Top:
Nikon - 2 wheels, mode dial (8 pos), 3 buttons, shutter release on-off switch. Status LCD
Canon - 2 wheels, mode dial (12 pos), 2 buttons, 2 wheels (one with lock switch), on-off switch. No LCD.
Back:
Nikon - 10 buttons, multi-controller, joystick.
Canon - 8 buttons, multi-controller.
So, looks like the Nikon has the extra complexity of an LCD display, 3 buttons and a joystick whilst the Canon has the extra complexity of four more mode options, and an unnecessary lock on the rear wheel (it's not needed with a wheel there like it was when the wheel was flat on the back, but it's gone into Canon culture), I'd argue that the feedback LCD and the joystick actually make it easier to use, because you can see your settings at a glance, and you don't have to fiddle with the multi-controller doing joystick stuff (ironically, and advantage Canon DSLRs have had over most Nikons) and I'm guessing that the three extra buttons don't make things to complex either. They are actually dedicated display buttons, whilst the Canon relies on the touch screen for those functions.
It's a true entry-level FF cam. Reviews seem to support this, as well.
Entry level and easy to use are not the same thing. The Sony A7III and Z have around the same number of controls, menus organisation is a matter of preferences. I've used both Canon and Nikon and both have their logic, once you understand it.