I use all three, cvs sterile cotton, kgd, and rayon, it just depends on which one I grab. flavor wise, they all are pretty dam close, honestly if I set up 3 of my kayfuns, all with the same juice, I really would doubt if any one could tell the difference. the differences are really in how one has success with a particular material, some may just not be able to successfully make a perfect build with cotton but they can make one with rayon, in that case of coarse the differences are major. like wise if one doesn't have great consistency with rayon but can make a cotton build perfect every time then sure that person is going to say cotton is better. seriously if all 3 wicking materials were done perfectly one would have to vape each one many times back and forth to find differences between each one, and even then, you might just be imagining the differences. there are some definite advantages other then flavor that each materials do have, like rayon, I do see it lasting a bit longer before having to re wick, also kgd is seems easier then regular cotton to wick a coil because of the flat pads, just cut a strip and go. my usual wattages are between 15 to 30 watts and all 3 wicking materials, with a good build, keep up fine. maybe it comes down to individuals particular taste perception but I have done maybe a thousand cotton builds, maybe a hundred kgd builds and about 60 rayon builds and tbh the flavors are pretty close imo. I never got the " I just received some kgd today and its 100x's better then cotton" or " rayon is such a game changer, its 1000x's better then anything I ever used before" or how about this one? " just did a rayon build at 13 watts, i could of never have done that with cotton". well i know for sure that last one is proof that the differences are not the material, but the build and how successful one is with that material.