The laptop has more storage and possibly better processors (i7 vs i5) so I'm not sure there'd be value in purchasing something with lesser oomph to it. Maybe she should just purchase a separate monitor she can use with her laptop? That way she can get more screen real estate and not lose storage. She can grab a 27 inch monitor at a reasonable price depending on her resolution requirements.
I stay away from trying to convince people to purchase a specific brand because it wastes far too much energy. We're an Apple household, I use Apple gear for photography work (though I'm not running a photography business like your wife) but it's a value decision for me rather than strictly cost. I don't do photography for a living but I do write software. Running a business can mean keeping costs to a minimum, though from experience, I'd be wary again of simply focusing on costs. What's going to help you be more efficient and get what ever product you do out the door in as high quality and efficient way as possible? What's not as likely to break, or if it does, what about customer service?
If I had to choose an HP that would be a good value (again, this is not a cost decision, but a value one) something like this would be decent:
https://www.bestbuy.com/site/hp-env...in-ash-silver-sparkle/6221032.p?skuId=6221032.
This has some room for her photography business to grow: 8 core I7, 16 GB of RAM, 2 TB of disk, plus a 500GB SSD, decent graphics and would last quite a while. It's still has touch screen if that's what she's after. But as you see, the cost pushes you closer to iMac territory. On the other hand, I wouldn't have to purchase a machine for a while, I could add additional storage or attach backup devices. I could write it off over a few years, and other business type things. It certainly doesn't have to be an HP, it could be a Dell or whomever, but those specs are certainly an adequate upgrade, certainly storage-wise and screen real estate.