I'm trying to make the same decision - iMac vs. Mac Mini.
I have the 2012 21.5" iMac and it has been great. I do photography and video editing (Final Cut Pro) - mostly family projects with some simple commercial stuff. The iMac is also the family computer with occasional multiple users logged in (fast user switching) and some shared folders accessed by other computers in the house. It has 16 GB and 1 TB (fusion) drive. It's been awesome, but it is time to replace it. I don't want to wait for the next M2 iMac and with the larger screen it would likely be out of my price range anyway.
In comparing cost M1 Mac Mini vs. new M1 iMac 24", I'd be starting from scratch, so for a Mac Mini I'd need to buy everything - keyboard, trackpad, speakers (about $300 there), and then a monitor which is apparently at least $600-800 (if not more) to get a 24" or 27" 4k with high pixel density and decent color. At that point, the iMac ends up being more expensive.
I use a MacBook Pro 15" for work so I know how good a retina display looks. I'd love to have that for my home photo/video work. I like the fantastic iMac screen, but the Mac Mini is tempting me too. It has more ports and may be cheaper to upgrade by itself. I had a 2006? white iMac before the 2012, and that one was great too in its time.
The new iMac colors are, uh, interesting. I could learn to like the blue or green, and there's always silver. The chin and the white bezels don't bother me, but I would like to see this in real life. When will they be in Apple Stores (or Best Buy or wherever) so I can see the iMac in person?
Beyond cost, upgradability and aesthetics, is there anything else to consider? The performance should be identical, right?