Procreate is definitely a potent app, holding its own against expensive desktop solutions.

I do have Sketchbook (from Autodesk) installed on my devices, however I don't find it as intuitive. Plus I'm not sure it has any option to export to Adobe Illustrator. To me, that's a big deal. If I can't easily export (with layers) to Illustrator to further refine the shapes or apply the vector art to a larger piece...it's a non-starter for me.

However, I do admit that Sketchbook has some nifty features that are unique to its interface. Someday, I'll probably blow the dust off and give it another whirl.