I always get exceptional customer service, with time-limited guarantees on all the hardware I buy at Cignot.com. Vicki is the best!
I mix my own juice (DIY), so I have no recommendation for pre-mixed juice. I order most of my flavorings from e-cigexpress.com and my unflavored nicotine juice from RTSvapes.com.
Reasons:
I only use Joyetech hardware, and Vicki at Cignot is a long-time authorized Joyetech distributor. I've never had a complaint that she didn't take seriously and tend to quickly. I suppose I should try others, but I'm totally satisfied, so why switch??
E-cigexpress has a wide array of flavorings from the best, most trusted flavoring producers. But mostly, they have an outstanding selection of tobacco-based flavorings of all types.
RTSvapes is new on my list, but the nicotine juice I've bought there has been very clean and pure, although I'm no expert on this subject. I used to buy it from Gourmetvapor, where I also used to buy a lot of pre-mixed stuff, but I've heard some stories that turned me off from that company. I won't spread allegations I can't support, but it turned me off. The one thing I will caution about buying pre-mixed juices from GV is that they post flavor combinations that are sometimes just experiments by customers who use their mix-your-own system, so it could be any old weird combination of flavorings that might be awful. I've had some real nasty ones from there, but also some very good ones. It's a luck of the draw kind of thing.