I've been using Affinity Photo ever since the demo, and have grown to love it - I now use it in work in preference over photoshop and I am considering getting Designer too.
There is a couple of things I would suggest changing just from my experience however, but these are very much minor things:
-I use the 'alignment centre/middle' tools a lot in my work, it's very convenient having it in the r/click menu, but I would love it if there was a choice that does both at the same time? Saves a couple of clicks.
-Square cropping. A lot of what I do in my work is convert images for Facebook use, and this often entails cropping them into a square. Currently, when you select the square crop, it expands the top and bottom (in landscape) out of the picture rather than (what I think is more intuitive) cut the left and right in. I hope that my description makes sense.
As I say, these are only very minor things, but I'd find them very handy.
Integration with Apple's haptic feedback would also be nice.