For photography, and because I print, my own priorities are (in no particular order)
* Panel image quality
* Color fidelity
* Color management capabilities
* Resolution / pixel density balance to edit images (to a degree, very subjective)
* Flexibility and options (a component of "Product design") - so connections, controls, things that help workflow, etc
Your three qualities listed above indeed only point to an XDR and if those are part of your "must-have" priorities, get that wallet out!
The XDR is indeed a lovely design (obviously very subjective), large screen, amazing contrast ratio for HDR, nice in-built color profiles and while the accounts are somewhat mixed, a possible "cheap" reference monitor. For color managed workflows, it gets a little murkier. With recent firmware you can do customized luminance and white-point tuning. For third-party devices and calibration, they recommend a spectroradiometer which is fairly high-end and expensive kit, but they say it's owing to things like peak brightness capabilities, most other standard tools probably wouldn't be as useful. I'd expect a newer i1pro 3 device could work, but regardless, you'd want to tack on some additional cash (>$1k easy) if managing the color at that level is important.
It's 6k, but obviously the day-day display resolution is going to be half that (though you can change as needed). It's less flexible than I'd like with controllability, but hey, that's Apple design ethos. It obviously only works with modern Macs, at least for now and that means one with a dedicated GPU, so if you go Mac mini, you will need an eGPU. I guess unofficially (and not supported by Apple), older Macs can drive this monitor to some degree but not sure of the implications.