Genesis Attys were designed around the use of a stainless steel mesh wick. With that wick, it is pretty efficient at pulling the liquid up to the coils through osmosis. It's only when the tank is low does the user need to tilt in order to bring the
juice to the top of the coils. There are people to prefer cotton to wick their gennies, but that is mostly for the taste that cotton brings. The absorbcy of the cotton actually doesn't bring liquid up as fast as the osmosis of the
eliquid in ss mesh.
Actually one of the most important pros for the top feeding of the genny is that there is almost no chance of flooding. Flooding and gurgling is almost the exclusive problem for bottom feeders.
One weakness of the gennies is that they can and will leak on you if you leave it horizontal or upside down. Also, the learning curve in building a ss mesh wick and coil is a steep one, requiring lots more patience than building a micro coil for a bottom feeder.
I use both. I enjoy my genesis because it's my Pyrex tank and allows me vape plastic cracking juices (versus the plastic window on the Kayfun Lite+). I also enjoy the crisp taste that ss mesh brings you. It's not *better* than cotton, but it is more crisp.