Another vote for the Buzz if only allowed 1 device. It's not really all that big, but it all depends on what you can deal with. It's certainly bigger than a standard 510, and holding it and using it is nothing like regular smoking or using a standard 510 or other e-cig. The thing is, though, that it's everything rolled up into one. You set it how you want it.
If you can't deal with the size, then my 2nd choice (which I'll grab for a trip to the store or for yard work) would be the eGo. It's great with a low-resistance atty.
If you can't deal with the size, then my 2nd choice (which I'll grab for a trip to the store or for yard work) would be the eGo. It's great with a low-resistance atty.