I’m curious about Concepts. Is it good for UX? Which options did you purchase?
I like the infinite canvas, but the powerful features for modifying lines you've drawn, and using guides etc are not that useful in my sketching, probably better for more finished drawings.
Paper by 53 + their new app Paste for a quick sharable link to present with. More hifi stuff - Adobe Comp is gestural based.
UID8 has an infinite canvas, hotspot linking between screens and online sharing of prototypes. Subscription with seven days demo. The concept is great but the drawing tools are rough.
Pattern has some interesting interactions and a neat list view tool. Free
Paper 53 is still my favourite to work with. Mostly because of the shape recognition and cut/copy tool. Free with additional features via subscription.