Affinity Designer is a very good vector editing app. Switched to it from Inkscape due to performance and UI issues. To me, it's more convenient to use than vector things in Pixelmator Pro.
For photo editing, I don't like Affinity Photo. It seems powerful, but too much for me to learn, so I use Pixelmator Pro for simple photo editing (although I can never remember where the tool I need is). Maybe it's better for pros, though.
For quick pixel editing/cropping I use Acorn — it's fast and the UI is not overloaded.
-- hobbyist experience
I've been using Pixelmator Pro a little recently, and I turn to it now for its AI features. Cutting a subject out of its background? It makes the "Magnetic lasso" feel like MS Paintbrush. I had to design a heavily 'shopped Christmas card recently, and those features cut down my work by a lot.
That being said, both products are solid and likely a matter of personal preference or specific feature needs.
Coincidentally, I just finished a session with Affinity Photo 2 before reading your comment.
I, too, recommend Affinity Photo as a Photoshop replacement for many people. It's probably good enough for 80% of people out there.
I switched to Affinity because I don't do subscription software. But I'm still up to speed with Photoshop because I have to use it at work.
Photoshop is still better than Affinity in a lot of ways, and for all the confusion in its interface, it's still more polished than Affinity.
One of my biggest problems with Affinity Photo is that it can't save files in the background, which wastes a lot of time when you're working with multiple large images.
Worse, though, is that Affinity Photo is just buggy. Affinity Photo 2 is better, but many bugs persist. Things like images loading, but simply not rendering on screen. Or selecting a tool, but the tool has no effect, and you have to quit the program and restart for it to work again.
Unfortunately, Affinity's official forum is not what it should be. I'll be polite and call responses from official Affinity people "brusque." Also, be very gentle in your criticism and reporting of bugs, because they're quick to delete even minor complaints. More than once I've been following a discussion where someone is having the same problem as I am, and I get an e-mail notification containing another person's response. By the time I get to the actual forum, it's all been deleted by the admins. Not a good look.
(It’s now available in v2)
I'd say it's much more similar to the pre- or early Creative Suite (not Creative Cloud) versions. (I'm using AP2)
One aspect gives a red flag though: they implemented internet activation in v2 as opposed to a prior simple licensing model based on license keys. So maybe one day they will start to force "cloud" junk upon the throats of their customers, and at that point I will probably just leave.
I use Procreate, Affinity and Figma and all of these tools are cheaper, easier to use, and still support my (often more advanced) use-cases.
Same with Lightroom vs. Capture One.
PS. If you fell for the same "annual but paid monthly subscription" scam with an early cancellation fee, try changing your payment method to PayPal, and then use it to block the payments.