This thread is quite fitting to what I'm trying to decide right now.
Presently I am shooting with a Sony A7 24MP (full frame) and been debating to upgrade to the Fuji GFX 50mp (medium format).
Reason for this is because I want to print big and want as much detail as I can and by going MF I wouldn't need to stitch as much.
Take for example this 15 photo stitch taken with Leica M240 24mp giving me 100mp
The disadvantage with going MF though is the initial cost and size of the camera and lenses.
Ultimately the final print will dictate the format that you will be using.
From what I've learned from others is that if you are just going to stare on a phone/computer screen and unless you plan to print bigger than 32x24 and close viewing, FF is more than capable.
Realistically, 24mp FF or APS-C is more than sufficient for my need.
For example this was taken with a Fuji APS-C 24mp and printed 32x24
And this was taken with a Sony FF 24mp cropped down to 12mp and printed 48x36
I shoot quite a bit with my Iphone as well and have no complaint since I know that I wouldn't need to print these bigger than 8x10.