I do almost all of my work in Illustrator (or at least I did before my free subscription that I had from school expired). So far, it seems like Affinity meets all of my needs and I'm pleased with it. However, at work I sometimes have had to use Photoshop. Mostly I just used it for resizing large groups of photographs to make them more appropriate a size for web display. I used a bulk edit trick where I could save a sequence of edits to a file and then just have all of those edits applied to all the files in a specific folder. Sometimes, though, I also had to crop out stuff to get a transparent background. Otherwise, I never really used it much.
So, do I need Photo to do these things, or will Designer suffice? I ask becuase I don't see anything like the magic wand selection tool, which was mainly what I used to remove white backgrounds when I had to, so I don't know if there's an easy way to do that in Designer. Designer seems to meet all of my other needs, though, so if it can do these other two things (or at least just the second), I'll stick with that. But if it can't, I think I'd better purchase Photo now, before the discount for it goes away. Save myself an extra $10.