Agree Leon is better than Ki at the moment, but Ki has the physical attributes to be better than Leon in my opinion.
I don't think Leon and Ki should be thought of as competitors for the same role. To me, Ki's strength is going forward. He is wasted playing deeper in midfield. They should co-exist in the same line-up and often do when JDG is playing AM behind Michu. I would like to see Ki in the AM slot in preference to JDG. With Canas coming in, Leon will be competing with him or playing alongside him. So that would leave Ki to play a more offensive role.
Looking at the way Ki was putting away chances on video, I think he should get forward more often and have a pop himself as well as trying to set others up. We don't have someone who's a threat from 25/30 yards and, if he could get one or two early next season, oppo defenders would be aware of the threat, close him down and create more space for Michu and the incredible striker/s we are going to sign. Like others, though, I don't regard Ki and Leon as being in direct competition in the team.
Ki does frustrate me when he doesn't take a shot from outside the box, as I thought that was his forte