If you have tried tons of different recipes and they are all bad, then it's probably not your flavorings.
It is either your bases or you.
What do your plain PG, plain VG, and unflavored nicotine (mixed down to your usual level) taste like when you vape them?
If those all have a neutral flavor or no flavor, then you have to go to HOW you are measuring and your process. There are a ton more questions to get to the crux of this, but those can wait until we know about the bases.