Click the "suppliers" tab at the top of the page and go to their DIY section usually. Most unflavored is good, it's when you get into flavored juices that things get unpredictable.
With unflavored, I believe all the juices are fine, it's their choice of nic
juice that can screw things up taste wise. If you wanted to get your own nic
juice, you can buy your own PG at a regular store and mix. As long as the nic is good, the final result will be also.
I found most flavored to be way too much, now I do the above and put just a few drops of flavored in, or vape it straight.