I want to second Sailorman's recommendation of the Apollo VV. Especially for the price, it's a great choice IMO for a very solid intro to VV, which is THE way to go if you're serious about vaping. It just is. Not many toasters are sold that don't let you have your toast either light or dark, and not many stoves are sold where the burners are either on or off.
There are some other great choices, but they cost more, and won't really give you a noticeably better vape. The Provari V2, Buzz Pro 2, Smoktech VMax, Reo (a different animal, the "bottom feeder"), and Darwin (seems to come only in "unobtainium") are some of the "usual suspects" for alternative VV choices.
There's one other device I'm going to mention (here it comes, Sailor lol), and that's the un-green yet way cool IMO Joyetech Twist. It's a sealed-battery device with a finite life, although my Joyetech eGo batteries are still going strong after about 7 months. (As a closet scientist, I just thought of a great poll to start; "How long before your Joyetech battery "loses its mojo?")
The Twist gives you 3.2 - 4.8 volt VV in a eGo-sized battery, with the 650mah being the one I would go with since the 1000mah is what I would consider to be "ridiculously long"). They come in black, silver, blue, white, and pink, and have gotten very good reviews indeed. With a DCT tank and a trim ring, they look great, and they're a very handy size for "stealth vaping" or out on the town. I use mine at home quite a bit as well, although my VMax is my "weapon of choice". That said, I have five Twists sitting in front of me in a cool little carousel, each fitted with a DCT tank with a different flavor in it, and that's as nice as it sounds. I have a sixth charging at all times, so the battery life - good but not "heroic" - is a non-issue for me. When I go out, I take a couple of Twist setups and a couple of extra Twist batteries, and sometimes the VMax + two extra batteries as well. I always have a spare Joyetech USB charger with me that I can plug into my ciggie lighter, too.
There's no one "perfect" APV. There just isn't. (Well, except for the ProVari V2 lol) But there are a lot of "no-brainers". The Apollo VV is one. The Twist would be one, except you have to get about three of them, but at $19 a pop, just do it, unless you feel very strongly about the "green" aspect of a quasi-disposable battery. The VMax is way, way cool IMO, but the jury is till out on long-term reliability, so it's kind of like buying a "growth stock" instead of something safer. But I o love mine - a lot. They come in black, silver, and either now, or soon, chrome as well. The Buzz Pro 2 has a reputation for being bomb-proof and performing great. The ProVari V2 speaks for itself; a legendary classic worth every penny IMO. The Darwin is in a class by itself as a variable wattage device, but they seem to be hard to come by, and I believe the battery is non-replaceable. (Sailor? That true?)
Here are some links and pics on the Twist. I do start people out on them, but I'm going to start "pushing" higher-end VV devices as well. That said, everyone loves them so far, and they've been doing just fine with two of them. I just remembered something important, and that is that I've been giving people just one charger, when they need two. Backup, backup, backup. And speaking of that, they need three Twists. And also speaking of that, you might not want to get just an Apollo VV. Or just a ProVari. Or just one of any device.
It's dawning on me that this is where the Twist really starts to shine. As a backup (A)PV that could also step in and "start the game", like a particularly good backup quarterback could. I just think they're so cool that I think everyone should own two or three. [Bites tongue hard].
Links:
THE EGO TWIST IS A GAME CHANGER - YouTube Grimm Green Twist Game changer
A PBusardo Review - eGo Twist - OvaleUSA - YouTube Phil Busardo Twist review
http://www.e-cigarette-forum.com/forum/new-members-forum/306344-first-post.html
(This thread contains links to every single thing you'd need to buy along with the Twists; I recommend Smoktech 3.5ml DCT tanks with Boge 2.0 ohm single coil cartomizers [a Bulli A2-TM atomizer would be better], a charger [two if this will be your only APV], a trim ring, and a drip tip).
Pic:
*****
About the Volt: It's on my list of "must-have" devices for the truly serious vaper, even though it's ciggie-sized, and constant voltage.
"Why?", you might ask? Because as vapers, I think we have a duty to help others save their health and lives by getting them off of evil, evil cigarettes, which I despise along with the near-criminals who make and sell them. Having a variety of devices to show to people, or ideally to hand to them and say "here you go, if you like it, buy it off of me" [then you buy another], is literally a life-saving thing to do. Some people just absolutely want a PV that looks like a ciggie. The Volt is a very good one.
Being prepared with a wide variety of gear you can help people quit smoking with is kind of like having a fire extinguisher or a defibrillator with you if you need to save someone's life. Something to think about.