I was also chasing for the best flavor I could get, strictly flavor (not vapor production or TH). There's two things that come to mind when I think about flavor.
rda's give the cleanest flavor you can get, but they are a pain as you got to drip constantly. However, using a bottom feeder makes dripping without dripping possible, so that's one route. A REO + RM2 combo is a lifelong solid choice. Second, it would be the
kayfun style RBAs. I thought dripping was the best it could get, but the
kayfun showed another great aspect regarding flavor. Due to the way it works and it's extremely compact chamber, it completely amplifies the flavor. Those two beasts will, IMHO, give the top flavor you can get these days.