I think nic level IS important but FLAVOR is equally important. I found the "marl" flavor I (unfortunately) ordered a large amount of to be tooo mild. However, I really love the strong, harsh flavor of "cuban tobacco" (24 mg). It makes my whole mouth/throat tingle. It's what got me off analogs. Some people swear by menthol flavors (even if they weren't previously menthol smokers). I personally smoke a menthol "blend" on a very regular basis. Sometimes it's it's the only thing that "does it" for me. (And I WASN'T a menthol smoker).
P.S. A good, freshly charged battery gives the best "hit".