Welcome to ECF! As far as juices, as a general caution, I'd try maybe some "multi-packs" of small volume of juices (like 10 ml) to try a bunch, many vape lines offer that option, including letting you choose flavors, unless you can go to your local vape shop and taste test some. I buy in much smaller volume ATM as I am still trying to find juices I like, and that has served me well. Same thing with flavorings for DIY, I bought small amounts to start, as if I hate something I'm either going to not vape it, or vape it (resentfully) so as to get rid of the juice, which makes vaping unpleasant, so it's not cool. When I DIY I also plan to start with small batches, as I'm quite sure I will make something(s) I find gross, and would like to feel less guilty when tossing it.
If you like nic flavors, everyone seems to think NET juices are the way to go.
Don't forget to experiment with your VG/PG ratio, you might buy some unflavored VG/PG so you can dilute/change ratios by adding VG or PG as needed, and of course your nic level will make a difference, too....
Hope that helped a bit, this is one area where recommendations can only POINT you in a direction, you'll have to taste for yourself
Anna