I bought my last 500ml batch from Best e-cig. I buy 36mg unflavored, and cut & flavor myself to 18mg menthol (Twice the juice for the money). Flavors are not my thing. I usually stick to one flavor, and the menthol really works for me. No complaints from Best e-cig.
Back in "The Olden Days"

I tried a few different flavors. I ended up going to a cake supply store and getting Loranns Flavorings to spike the flavors. They were OK as is, but I like em strong.