Affinity is great but there is also not as much training as PS, but for the price it is worth having. One thing that Affinity and PhotoLine can do that PS can't is make curves adjustments in the Lab color space without having to change the entire document from RGB to Lab. I am sure there are plenty of other things XYZ apps do better than PS, but I will say this again, PS has so much training and tutorials out there which save you time.

To be fair to GIMP, I used PS back to when adjustment layers were not a thing. The work that team does is amazing and I give them props (though I still would love to see adjustment layers).