If you're still looking for a cigarette-shaped device, you could try a 510.
But if you're really looking to step up vapor production, battery life, etc. then you should get a battery mod. High voltage (5v or 6v) gets you excellent vapor and a hit somewhat closer to an analog.
Here's a summary of most of the big-battery models on the market right now.
doots mentioned some much-loved models among users here. As long as you go with one of the quality-built, well-reviewed models (search for names on the forum), you can't go wrong. 6v is 6v. Just choose based on price, features, and the look you want.
I have only one, the Xhaler (from Nhaler.com). It does high-voltage as well as 3.7v depending on the batteries you put in. I like it a
lot. The Xhaler comes with 801 and 901 battery connectors in the basic package and you can buy 510 and KR808 adapters at the same time, so I can use four different types of atomizer. This lets you experiment and find which atty you prefer.
If it's not technical performance that ends up bugging you, but you feel like there's something 'missing' from the PVs/nicotine, then you might be missing the other alkaloids in tobacco (like the MAOIs). Check out the
Smokeless Tobacco subforum (stuff like snus, dissolvables, and snuff - i.e. spitless, safer and cleaner options, not dip). Supplementing with these things helps some of us keep the cravings away.