I have to agree on the Carto Tanks, been using them since 2 weeks into vaping. You don't have to fill them as often and the flavor is quite nice. Plus replacing a dead cartomizer is pretty simple once you get the hang of it. I currently use the 5ml tank and only have to refill it about once a day, but I'm also a heavy vapor. It does make the stick a bit top heavy, but once the juice gets down about halfway, it's not so bad. I do have a smaller DCT, I think it is like 1-2ml. I call it a "One-Hitter", it only lasts about an hour before it has to be refilled.