I recently bought a marker storage rack that I love. I've tried several solutions (cubes, bins, etc.) and now I have a rack that is similar to my other marker/pen storage units.
I have Copic Ciao and Sketch markers and this rack hold both. This rack is not a portable solution, but I don't need to travel with my markers so it's not a problem.
I sort my Copics by number not by blending. Also, I buy individual markers, not sets because too often I've found that when I buy sets of anything, there is always some colors I just don't use.