There are many e-cig/pv/apv out there, but to start I would recommend the following:
Cig look-a-like : Volt from smokless image
Better battery life (a step up) : Ego if you want a 650mah size battery (roughly same length as a cig-a-like, but bigger in diameter but are 3.4 volts
Another step up in battery life and power: Kgo/Riva/E-power, same diameter as an ego (standard sharpie) but longer and they are more powerful at 3.7 volts.
Another step up and you have all sorts of APV's to choose from box
mods, VV, hybrids etc.
I would suggest you start off with and ego or kgo and then find out what you like with them which will give you a better idea of what you would want if you wanted to upgrade. Good luck.