Does it have to be one that looks so silly? I would prefer one as close to a cigarette as possible. I know, I shouldn't be so vain and buy things based on looks, but whatever. =(
I haven't seen a single "cigarette" style/size device that anyone used for more than a week. The "pen" style/size is the smallest type that doesn't have major issues (charge time, output, doesn't leak,
refillable, replaceable atomizer). Refillable is super important to keep costs down. You replace your atomizers as they fail, you replace the juice when it's out.
There may be newer products that fit the bill without the issues, I just haven't seen them. There are new products released ALL the time since this is an emerging market.
edit: this is what I mean when I say "pen" style.
I just realized there's actual pen looking devices...
Anyways, there are a ton of variations on this design and almost all the parts are compatible. Three basic parts, battery (black piece at the bottom) and the tank and the atomizer (inside the tank, replaceable). I'd recommend the tanks/atomizer where the atomizer is at the bottom (near the battery not the tip). The OP basically has the newer/better version of the pic I linked.