It's always interesting watching people describe their flavor experiences with herbs. The flavor and fragrance do change based upon several factors:
1. Age of the plant
2. Time of day harvested
3. Growing conditions
Let's talk about those factors. We tell people in our climactic zones, 7 A-B, that we actually have two growing seasons for their favorite herb, Sweet Basil. In our zone we can plant young plants after the last official frost date, April 15th - yep same day those taxes due - and be able to grow and harvest their basil until about early July. The dead heading ( removing flower heads ) prolongs the growing of the leaves which is part of basil used for cooking. Now sometime in July the flavor changes as the plant has reached maturity and the dead heading is catching up with the natural process. The essential oils of the plant, this is flavor/fragrance source, start dwindling and now the plant is no longer tasty.
Solution is go find new plant and start over as the basil will be fine until our first frost. The age of the plant affects the flavor. Time of day references if the leaves are harvested early a.m., or afternoon or early evening. The oil of the plant is most abundant in the leaves at certain times of day/night and when the leaves are harvested that oil content is what you taste. Growing conditions such as is the plant being shaded by larger plant, is the plant actually growing rapidly, ie. new leaves require more water and the flavor is diluted, and how often being watered or allowed to dry. All of those factors influence the taste and fragrance. Bottom line of this confusion is try 'em, love 'em and enjoy 'em as you see fit!!!