I can give you an opinion as to soil Vs coco, but haven't done a hydro grow due to space restrictions. it's gotta be strain for strain comparison too otherwise youll be dealing with too many influencing factors... Even plant by plant, genetics play a role, so two seeds from the same bank could be wildly different plants.
My opinion is Coco > soil. I had more control over nutrients, pests, and airflow to the roots. Coco is also reusable/washable. Too many variables with different soils... I always had a problem! Flavour-wise, I think as long as you're getting proper and long flushes, there ought not to be too much difference. With hydro it is a constant feed, so less likely to get peaks and troughs in feeding and watering, potentially maximising yields. My two cents as well is that folx doing hydro tend to be using a lot more nutes and additives in general, which will certainly play a part in final product aroma whether you flush or not...