I currently have 3 I would classify as ADVs for me. All of them were (for the most part) "luck of the draw."
When I first quit smoking, and started vaping; I was dependent on a local vape shop for all my supplies (and education too). I was not yet aware of all the e-vendors, or ECF.
Finding a vendor juice, that I enjoyed for more than a couple of hours was driving me nuts. Tobacco flavors tasted nothing like smoking a cigarette, and yet, still made me jones to smoke... so those were out. Fruits seemed to run from okay, to down-right nasty; and nothing tasted good for long. I have never been a big candy fan, and candy vapes seemed like more of the same. Bakery flavors were just starting to come into popularity; cinnamon danish is about all I can recall... guess who doesn't like cinnamon?

My first ADV, and my not "smoking" saving grace, turned out to be a shop-made wintergreen mint vape. It reminded me of the Trident wintergreen gum I would chew on occasion. It was not a "knock you socks off" kind of vape; but it was one I could vape for more than a few hours without it becoming bland, boring, or outright offensive. It ended up becoming my ADV for more than a year; and is what got me started on my DIY journey. Like the gum; it was not something I particularly craved, but I none the less found it consistently satisfying.
My second ADV was kind of typical of how I find most of my recipes. I am a DIYer who is obsessively fascinated by what others are making. I can create from scratch; but I lack imagination, and dedication.

Out of the hundreds of recipes I have tried; I have found a dozen or two that I either enjoy occasionally, or were personally worthy of tinkering with to make my own. One was an ADV right out of the gate. That was Shortbread Biscuit.
I probably wouldn't have ever found the recipe on my own without a fellow ECFer mentioning it. It is a shortbread cookie recipe. I have strong childhood memories of Dad eating Lorna Doone SB cookies; which was unique because it was the only store-bought cookie I ever saw Dad eat. (Mom was one of the last of the "June Cleavers," to cook from scratch, three hot meals every day. She also scratch baked almost every sweet to be found in the house.) But, in my child's mind, "if these were worthy of Dad, they must be good!" I became a fan too.
I had probably not had a Lorna Doone in 3 decades; but when I saw the recipe, all those memories came flooding back, and I had to try. I had also just recently discovered Inawera's Biscuit concentrate and found that I liked it.
I have no Idea if it is really like the store made cookie (now I refuse to pay $5+ for a bag of cookies), but the recipe hits all the mental check boxes of my memory. I always keep this on hand.
The third ADV I have, and the one I use most regularly now; is unflavored (just PG, VG, and nic). This I found out of sheer frustration. I had been DIYing for nearly two years, experimenting with all sorts of flavor profiles, and nothing was even sounding good to me at the time.
I still needed my nic fix... nothing sounded good... "so why waste flavor concentrates" I thought. I made a small batch of unflavored, with the idea, that in a week I would be out of my rut, and could then decide what to mix. Lo and behold; I liked it!
Again; it doesn't fall into that "Amazing!" class; but it satisfies my needs. It is slightly sweet without being cloying. It has my nic. And, because it is flavorless, I find I vape a bit less (maybe; because my mouth/mind isn't chasing the fading flavor on my tongue?). It is fast to make, and it is also the cheapest, as it uses no flavor concentrates (often the first, or second, most expensive component in e-liquid).
Another benefit of unflavored, I have found for me, is that I now enjoy my flavors more when I choose to use them. I also don't need to use as much flavoring. Flavors are now much more of a "treat," and less of a "chore."
You are not alone!My taste buds are still recovering. Ive had the feeling a few times where I said to myself, yes this one is it! Then the next day I try it and I cant taste that wow moment again.
We have a pretty large professional craft brewing community, here in little old Boise. And, I enjoy visiting all the different brewers, to sample their latest releases. It is not at all uncommon for me, to really like a sample, then order a pint, only to find the extended/accumulative taste to become less pleasing. To me, it makes sense that e-liquids might have similar results.
Don't fret; just buy (or make; if you are DIYing) small sample sizes, until you can determine if it is going to remain a winner (or if it is worth your time trying to adjust; if you are DIYing). Set reasonable expectations for yourself. How picky are you? How likely do you think you are going to come across a keeper during a random testing?
I am in NO way, shape, or form; any sort of a expert, or connoisseur... of food, beverage, or vaping. However; I do enjoy the "experience" of dining. Taking time to discover the flavors that are present (at least the ones I can detect); to see if I can perceive what the chef was trying to put forth.
So, because I am picky/choosy/analytical/critical, with my food and beverage; it stands to reason that I would be with my e-liquid. I am not saying this is "good," or "bad," or anything at all. It only tells me that I am likely going to have to sort through more e-liquids and/or recipes, to find those handful of keepers. Realizing that; helps minimize my disappointment and frustration.
My ADVs have all been immediate keepers (at least worthy of a repeat). I may have needed some additional time, to make up my mind, that I would continue to like them. But, I have never had one I felt ambivalent about initially, that later became an ADV.How long after trying new flavors did it take you to find your adv?