If you're using a 3.3 volt
device like the Ego, a low resistance one would be best, probably also for a 3.7 volt
device. The Boge 2 ohm and Smoktech 1.5 ohm XL dual coil will give you a warm vapor and should get a try. The XL holds more liquid so it requires less topping off. The Vision Ego/Stardust clear cartos at 1.8 ohms will also work well but require a 510 to Ego adapter to fit non-Ego
devices. They give a flavor closer to dripping as they don't use filler. Just don't buy too many of one thing until you've tried a few variations out. All three of these carto types can be refilled right from the bottle. Good luck!