I like my DSE 901s from AquaVapor. They last a long time (for cig-a-likes) and they produce decent vapor and flavor. The 901 and 808 are thread-compatible so you can use any carto, atty or clearo that fits an 808, and you can get 510-901 adapters to use just about any cart or atty on the market with a 901 battery.
I've had my 901s for a month and vape them almost every day. One battery will last me half the day if I'm vaping normally (on my commute, on lunch break, sneaking a "stealth vape" or two), and they recharge quickly (under an hour, if plugged into the wall, longer if on USB on my computer).
I prefer the 901 attys and cartos to 510s. I think they are smoother, more flavorful and produce better vapor. There ARE 510 cartos and attys that perform VERY well (like the HH357) but they are expensive and hard to get.
Most of my "at home vaping" is done on a AcryliMax VV/VW mod. But when I'm out and about, I usually carry a few 901s in my pocket because they are easier to carry around, and I can carry 2 or 3 different flavors and switch them around easily if I want. Plus they are a lot more "stealthy" if I don't feel like fielding questions about my big mod, like if I'm on a focused shopping mission or in a hurry or something...
I haven't tried the Volt, but everyone seems to think it's the bomb. I may have to look into their batteries, since they would be compatible with all the 901-threaded stuff I already have.
One question: Is the Volt auto-battery sealed?