I have Ithaka, Kayfun 3.1 and Kayfun lite. They are all good, no leaking, no dry hits, but Ithaka is little bit more complicated to build and rebuild, you need to use resistant and nonresistant wire and on Kayfun 3.1 you will get slight whistling sound when you vape, I believe it is because of that air control screw. Kayfun lite is just perfect for advanced beginners, easy to build (only resistant wire) and no whistling. VTF is excellent on all three.