Who is the better artist?
I think Kakashi & Iruka would both be pretty average when it comes to art, but Iruka would be better at it than Kakashi. He’s always writing on the board to teach his class, and would need to draw diagrams & stuff, too, to help them understand the lesson; and I think with all that practice on the board, he’d have a steadier hand on paper. I’ve always seen him as more creative than Kakashi, too (you’d have to be pretty creative to come up with all the pranks he did as a kid!); and I think his imagination would help add life to whatever he decides to create.
Kakashi would be able to learn certain things by watching with his sharingan; but I think there’s more than just technique with art, and some things that Kakashi wouldn’t be able to copy; so when he tries to draw or something, he wouldn’t necessarily be able to produce stunning images of what he has in mind.
In saying that, though, I think Kakashi would be very good at Pictionary, because I can see him being able to visualise each object as their base shapes (eg. an ice cream being a triangle with a circle on top) since that is something he’d be able to pick up on with his sharingan; and he’d be able to sketch out a very basic drawing of something very quickly, which is all you need for Pictionary! Iruka knows to always be on Kakashi’s team if he wants the best chance of winning 
What are your thoughts?