Perhaps it's a just me, but I've never met someone who uses Affinity Photo as their main digital painting app. The one artist who doesn't use PS actually uses Clip Studio Paint.
I'm not saying it's not a great app (I'm not familiar with it enough to judge it). But if I'm not using an open source one, I'd use the industry standard one.
I'm not a real artist. I do programmer art for game jams, MVPs, UI mockups, etc. I always liked Affinity Designer on iPad for that. It's got nice Apple Pencil support, it was inexpensive, and it works with other file formats pretty well.
Last time they had a sale on their "Universal" bundle, which got you Mac, Windows and iPad licenses for all their products for $100, I had just received some illustrator files that I wanted to work with on my desktop and decided to go ahead and pick that up.
I now find myself using Photo and Designer instead of Krita/Gimp and Inkscape, because I'm more efficient with it as a non-expert user and because the .psd and .ai interop is better.
I need to deal with one of those two file types approximately 0.75 times a month, so the industry standard one feels eye-wateringly expensive. But a one-time $100 fee for a less frustrating experience than the open source ones offered felt worthwhile to me. And they've grown on me to the point that I pick them up when I need to make something for a game jam, not just when I need the interop.
I am a pro artist. Most of my artist friends who don't use Photoshop either use Clip Studio or Procreate. In general the Clip/Procreate split corresponds strongly to whether or not they do a lot of comics.
There's a handful of other programs that one or two of my friends use but absolutely zero of my friends have talked about using Affinity Photo.
