My advice to you is to read up on the different types of devices and juice delivery systems available. This is a good resource for someone looking for information....http://voices.yahoo.com/types-electronic-cigarettes-beginners-guide-to-12685865.html?image=2809786&cat=5...
It is a guide for beginners and explains the different types of devices, how long the batteries last between charges and some of the terminologies.
Your success depends on what you feel you need to quit. Do you want a device similar to a cigarette or do you want to go away from anything resembling a cigarette? It's about personal preference, some people like the smaller cig-a-like devices while others prefer to start out with a longer lasting battery like the "ego battery".
Once you have an idea of what you want, find a local vaping supplier and go in and ask to try a few devices and sample some juice. Many of the shops allow you to try before you buy. That way you don't end up with something that could be a waste of money. You'll have already tried it and will be satisfied with your purchase. The "best electronic cigarette" is really just the one that is right for you, the individual. I wish you lots of luck in quitting, I have used an electronic for 1 year now.