For effectiveness, it really depends - wife and I smoked 1/2-3/4 packs a day, both of us started at 12mg nicotine, kicked it up to 18mg before we were able to quit smoking completely. She still vapes 18mg, I cut mine down to 12mg and then 6mg at night - the last few months I'm finding I rarely want to go above 6mg, ever.
You're an interesting case, in that you don't smoke - if I read your original post right you're tempted to go back to cigs after having given them up for a couple years. While most of the time everyone recommends higher-than-normal nic doses to get people to quit smoking, in your case I might suggest starting at 0 nic or a really low level, to see if it's the act of smoking or the nicotine that's drawing you in. If you don't get the satisfaction you're looking for, you can always go higher later.
Because you don't know how much (if any) nicotine you want, and because everyone's tastes are unique, don't buy a lot of juice up front - if you can find somewhere with a handful of small, cheap samples, play around a bit.
I'm also going to recommend the Ego - the cigarette-sized devices, in my experience, have been crap and failed to help me when I tried to quit using them. I still use Ego twists, and I'm perfectly comfortable with their performance, not to mention the wide array of juice delivery devices they let me try (others have mentioned the limits of the miniature setups). If you were an active smoker plowing through a pack a day or more, one of the big, fancy devices might be more up your alley...but then again, lots of people like that have also quit no problem with the Egos.
Do your homework, set your budget, and then have fun. Best of luck in whatever direction you decide to head!