If you are going to chain Vape you need an 18650 battery mod! This big battery will support chain vaping and really the best choice if you need something with the best battery life! Also, after a year or so when your batteries die, you just buy new ones; no need to buy a new device! So as a general rule, start you search with that kind of device! Also a variable volt device will give you the ability to control or adjust the amount of vapor you want. The Lava tube is a nice device if on a budget. Provari is also the class leader and you will pay for it, but it's the kind of device that lasts forever! In fact they also have the Provape 3.7 volt alternative that has a lifetime warranty! Joy tech 18650 is my favorite (inexpensive) chain vaping device but buy 2.0 ohm caromizers at minimum to get tons of vapor. I would also recomend getting a tank system if your chain vaping! You will go through less cartomizers because it keeps them moist all the time! I have a Liquinator Tank but their are lots of choices!
So if money is not an issue the Provari is the top choice!
The Lava Tube will accomplish the same goal for half the price!
The Provape 18650 is solid device, just keep in mind you can not adjust voltage, but the quality of this device can't be beat!
Joy tech 18650 is a nice device if you are on a ultra budget and need something that allows for chain vaping!