Well, where do you start?
Well first I should start with the disclaimer that I don’t do any photo editing so this reply is full of assumptions. But as I don’t play for a Premier League team and that hasn’t stopped me commenting on Saints, here goes…
Most modern consumer PCs with plenty of RAM will do a great job of basic photo editing. You really don’t need too many smarts for that.
However, if you do a lot of photo shizzle then perhaps the most important thing to get right is to get a true colour calibration on screen? Spend on the video card and monitor in that case. There is a type of monitor that is better (more expensive too) than others for that. Can’t remember what it is, will Google later.
A general recommendation would be to go for plenty of RAM and lots of storage - either all SSD - (although that is expensive) or hybrid SSD/mechanical. As a minimum, I’d have SSD for the operating system and swap space, and then a large mechanical drive for photo storage - and that large drive should be a hybrid SSD/mechanical.
If you do lots of batch processing of images that apply lots of filters to each image then CPU performance might become important, but if you apply piecemeal filters to individual images then a high-end consumer PC should be fine.
I’d also invest, if you haven’t already, in a large amount of in-cloud storage with automatic sync for the photo data. Don’t rely on having to upload stuff to Google/Apple. Oh, and go for a mix of USB (3/2) sockets and perhaps inbuilt SD card reader.