Heads up if you have been on the fence about getting Affinity Photo on your iPad. Serif just released a new version today, with what looks like significant improvements, and they are having a 4-day flash sale at 30% off.
As this is positioned as a pro-level image editor, be aware that there is a learning curve to mastering it. I am still reaching for Photoshop on the Mac out of habit, but am determined to getting better at Affinity Photo as well.
I can’t compare the two but I know Allison Sheridan did a lengthy screencast of Affinity on ScreenCasts Online. If not a subscriber, you could use the free trial to check it/them out. I’m guessing there is a Pixelmator one but have not looked.