Probably neither. Illustrator and Affinity Designer are a lot more featureful right now. Sketch is much more geared toward UI design than this is. I think the itch this scratches is:
Free
Great for those situations where you want a tool that is better than Sketch for illustrations or iconography
Integrates into your workflow if you like to sketch ideas on an iPad and move over to desktop
I don't think I'd consider this a "pro"-level design tool but for the price tag, you might as well take a look.
Probably neither. Illustrator and Affinity Designer are a lot more featureful right now. Sketch is much more geared toward UI design than this is. I think the itch this scratches is:
I don't think I'd consider this a "pro"-level design tool but for the price tag, you might as well take a look.