Here is some information I put together in another thread for a new person wanting many options. At a minimum, I would get either a Kgo or E-Power. Both are good beginner PV's that will give you about 6 hours on a charge and much better batteries than the over-hyped eGo.
Here are three suggestions in order of good, better and best:
Good:
E-Power 510, Kgo or EVO. I like the E-Power because the batteries last a little longer (lifetime wise) and cost 4 time less. Both the Kgo and E-Power are 3.7 volt/1000+ mAh batteries. All three of these are better than the over-hyped eGo which is only a 3.4 volt/650 mAh battery. Stick with manual batteries for better control, better warmth and safer. Battery life on a charge is about 4-6 hours. The EVO is selectable power allowing you to choose between 3.7 volts, 4.5 volt and 5.0 volts which is a simple set-up that provides the three main power levels:
e-Power
Electronic Cigarette - Starter Kits - EGO E-Power
EVO 2.1
Shop
Better:
5 volt GLV 2: with a 5 volt PV you will get long battery life (6+ hours) and much warmer vapor. The GLV come with a lifetime warranty and is built to withstand a bomb hit. Few models can match it's build quality:
Electronic Cigarettes and E-Liquid - Great Lakes Vapor
Best:
Variable Wattage Darwin (if you can find it in stock): with the Darwin you can "dial in" your power settings to get the best vape from any atomizer, cartomizer and eliquid. It also maintains your setting automatically when the resistance of the atty changes from use. It also has "regulated boost circuit" technology to maintain your power setting even as the battery drains. Most impressively, it gets 21+ hours on a charge. It comes with a 2 year warranty (which is rare) and a full year warranty on the battery (which is unheard of).
Darwin:
Nhaler
Another good option in this category is the ProVari variable voltage model.
Good Luck
Note: Rule of Thumb: the more it looks like the real thing, the worse the performance.