I got a recommendation when I first started along the lines of "Your tastebuds are messed up. Just stick with some simple juices to start. Don't spend more on juice than you need to until you feel your taste coming back." (I'm sure you've read some descriptions that just make you drool.) I don't entirely agree with this, but shopping based on affordability alone certainly knocks out a lot of options and makes the beginning search more manageable.
I got an order from Mount Baker Vapor last week, and I liked some and gave away a few others. I've also tried pricier juices and had similar feelings (although I'm not giving THOSE away quite yet). Other advice I've received that I'm really starting to understand and appreciate is, "Just try as much as you can that sounds tasty. Don't trust reviews of what people like and don't like: pay attention to their
descriptions of flavor and the quality of the liquid."
One piece of advice I have is that you need to get a rotation going. Most custom juice orders need time to settle and age (usually called "steeping"). Its hard to build up a rotation of liquids, because 1) liquid is not free, 2) shipping isn't free unless you spend a good chunk of money on a one of a few particular websites, and 3) you have to wait anywhere from a few days to two weeks or even more before the juice will taste as yummy as it is meant to be. There are methods for speed-aging, but I've had limited success with these, so I can't speak to their effectiveness. If you look around though, people have all kinds of tricks that satisfy them. Eventually, you'll find some that you enjoy straight from the mailbox, too.
I know that I haven't recommended anything in particular. I agree with Moonlit_Water. Ordering online can be risky, so make sure you order with shops that have GOOD reputations. There's plenty of other threads on here to find many more reputable sellers. I think we're living in a liquid renaissance.