The rayon/titanium combo is the best IMO. As for the build, I like a single coil that is spaced out with none of the coil wraps touching each other. I use 28g titanium and it's not micro. I use a 7/64" size bit to wrap. I am able to put a good amount of Rayon inside the coil.
With this build I tried just tucking the rayon inside the cup and leaving the channels empty. It didn't work so well. I could not get it to stop gurgling, even with the juice control barely open.
I did the same build and cut the rayon at an angle so there is only a little bit of it going in the channels and not really anything sitting in the cup.
With this set-up the juice flows nice. I don't even worry about the juice control that much. It can be open a little or a lot and it just works. I don't even close the juice control when I am not using it. But I do have a habit of shutting and opening the juice control when I pick it up after I haven't vaped for awhile. Just to see where the juice control is at. Because a few times I start vaping and didn't realize the JC was off, which can cause a burned wick.
I also try to keep the tank filled. If I vape it until the tank is empty then I might get a slightly burned taste, which is no good and it will ruin it and then the wick needs to be changed.
The coil is 0.6 ohms on Esterigon. I think I am on day 8 with this build. [emoji4] And still going strong with no burn flavor.
Imeo is right about the slightly open lips for bigger clouds. I also keep the AC fully open.