This one is my favourite, I think (put in NSFW tags for avoidance of repeat post)
But then I go back and look at some of the others and change my mind!! :D
All brilliant
Recently I have really been digging Mondrian paintings from around the midpoint in his career where he seemed to be a mixing naturalistic scenes and the completely abstract stuff he got into later. This is one of the best examples I could find online.
Why? Its sublime