As everyone's tastebuds are different you can certainly read flavor
reviews on various company sites. My recommendation would be trying small quantities from DIY flavoring companies and flavors that I GENERALLY enjoy (sometimes layering from different vendors) would be mango, apricot, boysenberry and berries generally.
If you are looking for premade juices I can't be of much help as I have almost exclusively DIY. I will say, try some small tester "fruit samplers" from various manufacturers to get a
sense of what y you will like, or not. For example I can't tolerate orange, at all in any mix I've found. I hate it all, etc.
A flavor tasting bar at a brick and mortar may be of use if you have such a thing available to you, etc.
Good luck,
Anna