If juice tastes better with lower nic levels, it usually means their nic base sucks.
I've been DIY juice a long time and have yet to find my juice tastes any different at different nicotine levels. (TH is directly impacted though, which is what is should be.)
'Scuse me, Hoosier (and a sucky nic base may very well be one reason juice tastes better with lower nic levels), BUT we have one vendor here who has a nic base already made up, and a flavor base already made up. What they do when they mix juice is add one of those to the 10 ml bottle (eyeballing it), then add the other to fill it up. This means, of course, that the higher nicotine you ask for, the less flavoring they add to dilute it. The less nicotine you ask for, the more flavoring is added. I noticed this pretty quickly last year. I bought a menthol juice in 6mg and later decided I needed to bump up to 12mg for a while. I didn't like the 12mg nearly as well as the 6mg. One day when I was sampling flavors there, a lady came in and asked them, something like..."Does the higher nicotine mean less flavor?" They confirmed this.
Ideally, that isn't the way it's supposed to work, but I guess most people don't notice or don't understand, or whatever...