I use fasttech almost exclusively from China, to me they are the most organized and reliable vendor and usually have many things in stock. Unless it's DIY stuff or something I want/need immediately, I will often use FT for many things. I have learned to expect a wait and I've only ever had one item be "out of stock" and they sent the rest of my order then shipped the rest the next day, actually. They really do try (IMHO) to be user friendly and offer some of the best (Chinese) customer service around. They fully disclose clones and authentic, and it's been accurate for me.
I have also used 3FVape with success, and they do offer a good selection as well.
I used gearbest-- once. I won't go into my rant about them (and, it was partially my fault) but I will NOT be using them again, their TOS do not work (for me).. I've heard decent things about 2Fdeal, but I haven't actually used them. I would run from Vapsourcing like a kid runs from a rabid raccoon, but again, that is only MY assessment of them, I know folks have used them with some success and they do have a pretty wide selection.
FT also offers incentives like bonus points, they keep all your orders on file in case you need something again, and etc. I also like that there are message boards where you can look at say, clones, and get good feedback on them and etc.
Really, FT has NEVER not delivered on an order, and usually my arrival time is less than 3 weeks (as long as it's not Chinese New year or something.) Usually you can find a discount code somewhere on ECF for them as well.
I would rate FT as my number one Vendor for China and I hope it stays that way.
Anna