Really? They seem to target different kinds of users. For illustration work Affinity Designer has the edge but was still pretty badly suited for the kinds of UI design work people usually do in Sketch. Or at least that was the case the last time I tried it.
Affinity is focused more on graphic design while Sketch is focused more on interface design. The price difference is a huge issue though...Sketch needs to drop their price back down to $50 if they want to remain competitive.
Sketch 3 and Affinity Designer are two completely different markets. Sketch is a vector editing program (competing with Adobe Illustrator and Inkscape), Affinity Designer is a photo editing program (competing with Photoshop and Pixelmator).
You're thinking of Affinity Photo. Affinity Designer is probably closer to Illustrator than Sketch is, since it's geared towards vector illustration rather than UI design.
