I spent an incredible amount of time thinking about how to quilt it. In the end, I just opted to machinequilt around the shapes.
I changed the way the binding was done, because from the very start that small line around the quilt bothered me. I feel it didn't fit all the squares and the busy quilt. So I added rectangles instead of squares at the exterior and used those to finish of the quilt. I have to admit the upper one does have a tendancy to faint but I can live with that, since the quilt is meant to be used.