You should try the single coil SmokTech 1.7Ω cartos.I've ordered dual coil and triple coil. When I get them, you can check in the HC forums, I promised to post a review.
All this talk about triples and 5V is kinda silly. To actually vape them at 5V means you'll need ~3.4A of current. I know of no 5V device available that can supply that amount of current.