How about.....
D. None of the above?
Check out the youtube reviews of the Expromizer!
I believe every single reviewer feels that the Expromizer provides better flavor then the Kayfun!
I own two Kayfuns, and have loved them! They're easy to build, provide great flavor, tons of vapor and never leak. What more can you ask for?
Well... how about air flow control which you can change, without the need for a screwdriver or other tool? How about the ability to rebuild your atty, or add juice, without the need to empty the tank of it's existing juice first, much like a Taifun? (The build on the Expromizer is EXACTLY the same as on a Kayfun).
How about a catch tank on the bottom, so if your tank DOES leak, the juice is caught in the catch tank, and doesn't spill all over your device (never had this problem with a Kayfun, however...)... a 510 connection with a spring?
It even has the option to purchase an extended tank option, which will hold 8, that's EIGHT ml of juice!!!
None of this matters, if it doesn't provide flavor and vapor production as good, or better then a Kayfun.
I really believe that the flavor from the Expromizer is as good or possibly even better then I get from RDA's. I don't know if it's the larger fill channels, or the larger chimney or what it is that provides better flavor then my Kayfun, but I'm telling you that it does, and just about every reviewer I've seen agrees.
Check out any of the several youtube video reviews and see if it won't fit your needs. It IS a bit larger in size then a Kayfun, and it's more expensive then a kayfun clone, but less expensive then an authentic kayfun... so you need to decide if it's worth the price.
Good luck! (oh... picked mine up at LibertyVapor)