If any vendor reads this modest message from me: please stop with the packing peanuts. Stuff that teeny box with some paper, please.

I'd have to give "Best" to Bull City.

They have good prices, a huge selection, and they ship so fast you'd swear they are hiding a time machine.

The customer service is second to none, and should you have any issues their staff is great about getting it resolved in a satisfactory manner. I've never had to wait long at all for their support to get back to me.

Their packaging is great, my bottles typically come in zip lock bags to prevent a mess if a bottle should happen to leak in transit.

With all that being said, there are other good vendors as well.

Shout out to DIYVaporSupply for having just a crazy selection, even if their prices and shipping isn't the best it's okay, because they carry weird flavors you won't typically find at other vendors.

Also shout out to River Supply, for selling 15mls at good prices. River's selection is pretty good as well, they carry a few things BCF doesn't, like (some) FlavorMonks and Purilium/River flavors. And they have nic, which can make them a convenient one stop shop for people starting.

For the EU folk

Chefs Flavours is the place to go.
Prices are always good.
They have the largest selection in Europe by far.
Customer Service is always top tier. Have any issues, they'll resolve it ASAP and are always nice to talk to.

They package flavors responsibly, and shipping is fast.

The only issue is, now that Brexit happened - You can run into some import taxes, when ordering from the EU. Some don't get hit with it, but some do - So just take that into account when ordering, if you're located outside the UK.
I'll suggest placing a large order, so you get free shipping - For me, even when I had to pay €35 Import Taxes, it was still cheaper than buying locally.

Can we add some European, non UK vendors to the vendor list? With covid and brexit customs has really tightened and importing from UK is almost impossible without getting stuck in customs.

I live in France so i found a French vendor who does 2day delivery to France, i imagine other European countries shouldn't take that much either. A bit pricey but given the current situation i feel like it's worth it.

Bull City Flavors - In the USA, BCF is the best. I always go there first, because the price will be good, the selection will be great & I will receive my order quickly & undamaged. I'm over 600+ flavors in my arsenal now & I would say BCF delivered about 90% of them. I don't know about their order resolution because I've never had to contact them about a problem, they got it right the first time. As for customer service, I have reached out to them before with questions & a next day response is the usual outcome.

DIY Vapor Supply - is my go to when I actually can't find what I need at BCF. They have some obscure flavors in their stock and hard to find flavors if you are in the US, including some Chef's Flavours, Faerie's Finest & Solub Arome. Be forewarned the website's naming convention for vendors is a little strange there, for example, if you are looking for TFA (or TPA), you won't find it alphabetically in the "T" section, it's hidden under "DIY Apprentice", so if you can't find something, poke around.

River Supply - is a great stop for flavors if you need to buy nicotine too. Their nicotine prices are the best that I've found. I'm not familiar with their River line, but their Purilum line is great & they carry about 20 other vendor flavors there. Super easy to get free shipping there too (spend $50 you got free shipping).

Chefs Flavours - Some flavors you just cannot find in the USA (yes, I'm looking at you FA Custard Premium), so going overseas is your only choice. I've only done this once & I have to admit, I was a bit disappointed by the selection on hand, a lot of flavors were out of stock, on another day maybe I would have been able to get what I wanted, but I was able to get the majority of what I needed & shipping was quick & inexpensive considering the distances involved.

Honorable mentions -

Liquid Nicotine Wholesalers - their nic is just as good as River & priced the same, they have oodles of DIY supplies & if they had a better selection of flavors I would have rated them above River.

Wizard Labs - not quite the selection of BCF, but they do carry vendor lines that BCF doesn't & they sell nic/lab supplies.

River has treated me very well when I had an order issue. They fixed it quickly. Decent flavor selection and nic.

Bull City. Super fast shipping and great flavor selection. They're always happy to include a free sample of something new to try.

LNW. Never had an issue with their Nic. Clear, tasteless and cheap.

OOO. Fair to moderate shipping times but almost instant response from customer service when I've had questions.

Chef's. Simply the largest one shot offering I've come across. If you can't find something to vape here your internets are broke.

Edit, since this is specifically looking for Best, I have to say it's a tie between:

Bull City Flavors and Chef's Flavours.

Wizard Labs has done me very well. I use them in the summer. Liquid Nicotine Wholesalers, River Supply and Bull City in the winter months. Delosi has good nic as well. A few years ago there were some issues and I got one bottle of yuck nic, no issues since.

Nude nicotine is a simple no brainer. But be fair warned that they are super slow but for a few extra dollars they have a first in first out deal. If you do the deal just order the nicotine and that's it. Me just order a couple of months ahead of time and you'll get it no longer than 60 days. They have a 1 time sample deal also but I'd say skip it and get a 50ml for a test instead. I've got a high quality freebase and salt from them. Some other options are available for flavors and stuff. They have a very good stevia solution that is very clean tasting. From the little I've seen of the various sites they may have the best option for the way to get it.

Have not tried but bull city might be the best place that doesn't sell nicotine. The first thing that you really get on this company is that it super fast and has a high level of respect in the community. Has 10ml size and up. They're probably going to be ok with buying from after the mail ban. Don't forget the reddit code check it out a couple of months ago and still work.

River supply co. I think of it as a lower quality version of Walmart but for diy ejuice. I did get some bad flavors from them and they were hacked and never informed the people's who information was taken, got a ransom email and they then tried to purchase something for about 4 Grand and since I have never bought anything over 800 they realize it was fraud and froze the account.
Had issues with both orders and I was very pleased with how they handled it. But because I had the issue with the order before I could even try the flavors I never brought it to there attention and fully believed it would have been handled in a very professional manner and it shouldn't be counted against them. There 2 brand of flavors has gotten a bit of attention in a bad way and good. People have said that they don't mix well with other flavors. I have not seen any faults with mixing with different flavors. But the lemonade and strawberry lemonade are tricky to use and for most people should be avoided. My favorite strawberry is perilum ripe and sweet. If fast enough euro flavor grapefruit is on sale and I'd say buy a big one or two before they stop selling it. Useful for lemons and oranges for sure and eleswise. I would get what you want to try and get the free shipping and do a separate order for pg,vg,and nicotine. I would go ahead and get the most that you can afford for those 3. I bet you they will be messing with those at some point this year and remember that the Democrats are pro weed but anti vape and tobacco. They r also slower but will send out multiple packages and not make you wait if they run out of a item order. One stop shopping and cheap nicotine is the most draw inspiration for them and good policy for mistake.

I do have a vendor who I won't recommend but is ok for cheap nicotine for those who are gamblers on how long it will last. I am still vaping on 6 month old sample that is just left out in open. So for the price if you only use bit less than half then you'll have gotten a great deal. So PM me if you want to know who. I don't log in to often but I will try to before March 1. Ty

Living in Israel, the best vendor for me is Nom Noms - a decent selection of flavors, lowest prices in the UK, reasonable shipping costs to Israel, customer service replies on the average within 30 min and is very helpful in resolving problems, etc.

Many here like Bull City. Maybe I would too if they were shipping to Israel. For some weird reason they do not.

I've ordered from Bill city a few times. They have a lot of different flavors and they ship fast. I went with them after I found out that they carry wonder flavors.

Bull City is the best - as a vendor, they are head and shoulders above the rest. Definitely the go-to for flavors

Heartland Vapes - my go-to for nicotine. The regular is 'unbranded' but I've been buying from them for years with no issues. They also now carry CNT and Chemnovatic (that Vaperstek used to sell). Good packaging and ship times

River Supply - pretty decent runner-up. Flavor selection is good, packaging is good, and their ship times are decent when you don't order during a massive sale LOL.

I've also ordered from Wizard, FJ (formerly ECX), LNW, LB, DIYFS and a few others - no serious issues with any, just nothing outstanding either.

Outside US: Chef's has a good selection, fabulous customer service and great shipping times.

Nom Nom's UK - also good selection and great shipping times. Never contacted their CS so I don't know about that

E-aromashop - All Inawera resale. Good prices, good shipping, good CS. My go-to for INW larger orders

I've ordered from Bull City Flavors and River Supply Co. multiple times. I like them both equally. I'd say if you need nic and flavors go to River Supply Co. first since you can get almost everything there. They have good prices for 15ml flavorings and they have the cheapest nic. I like their bottles too. Bull City carries flavors that River Supply Co. doesn't though and they will help you if you need to fix an order.