I love drawing expressions and faces in general. Crazy expressions are a challenge, but also so much fun to do. I also love drawing fluffy hair (coloring it is a different story, tho). Most of my characters end up with their hair being floof. 
I dislike drawing urban backgrounds, like cities, rooms and all that man made stuff. With landscape I can improvise and pretend that green blob is a bush, but with cities it looks just silly. XD Also feet. No. Just no.