I have a Smok e-Pipe clone from Fasttech. Kinda restrictive in my opinion, and suspect if you in an area that is not welcoming of it. I already got told to put it away by shops when I was using it, even when there are other people
vaping at the same table and battery life isn't that great, seeing that it takes a 18350 battery.
Not a big deal since I keep it at home, just to play it safe. Because of the angle of it and for some other mods, it's best to use tanks or clearos. I'd use a Protank Mini, but my mod only has a 510 and no Ego threading. I'd have to buy a 510 to ego adaptor, but I'm using a Mini Nova tank, so it works pretty well since I tilt on occasion.
For other models, There isn't too much selection, especially with variable voltage/wattage. There's one the PBusardo reviewed that was pretty awesome, but extremely pricey for what it is. Well worth it if you are into that, though.
I like it because it is different from anything else in my case. It has it's definite flaws, but nothing too major like I've described above.