Both are quite mature products these days, with subtly different emphases.

As with this release, Pixelmator Pro has prioritized ML-powered tools and has been an early adopter of new Mac technologies like utilizing the neural cores on M1/M2 processors.

Affinity Photo is in some ways a more traditional photo editor, and its biggest selling point may be its integration with the other members of the Affinity suite, Affinity Designer and Affinity Publisher.

I quit Affinity Photo for Pixelmator Pro a while back because Affinity Photo is quite a bit slower, and because it mostly just copies Photoshop’s UI, while Pixelmator Pro rethinks and improves the bad parts of Photoshop’s UI while copying the good. In the past Pixelmator (before the Pro) was lacking features, but Pro largely addressed that, and they continue to ship significant improvements regularly. Affinity Photo recently came out with a 2.0 across their suite which may have addressed the pain points, and I’d like to try.

Affinity photo has too many quirks and (small) glitches for me: one of the most annoying is that ALL tools/inputs reset to default values/state after single use. It also becomes imprecise when working on smaller images (not photos): it’s not well suited as a pixel editor. It allowed me to abandon Photoshop a few years ago but I’m not much satisfied.

I use Affinity Photo because when I wanted to try Pixelmator I discovered they only sell the product on the Mac App Store and I strongly dislike the App Store. Affinity lets me buy direct from their website.