It's a common misconception that cotton is a great wicking material. It's not! Cotton does expand when it's saturated with juice, it's true. But for capillary action, cotton does not vertically wick as well as mesh. Don't believe it? Roll up a mesh wick and a cotton wick, hold them side by side with the end in a cup of juice. See which becomes wet at the top faster. The mesh will. The mesh won't hold as much juice as the cotton, but the capillary action is faster. I use cotton in drippers, where the wick is horizontal, and is fed from above; but I'll never use cotton in a bottom fed device, such as a genisis.
Meh...
I am happier with cotton over mesh BC the cotton, holding more juice will work for harder longer drags, then it may take a while longer to rewet but that's going on between hits, and it holds more juice so you have way less chance, and you have to work harder, to get a dry hit. Fmesh! My 2 cents..