Best Cognac

Normandier-Mercier is too sweet. I simply do not believe that it is unmixed Cognac. Delamain Vesper is a bit dry and has too much fire. However Delamain Tres Venerable is great (don't expect sweet nectar) it is not, it is a "real thing" with no 'sugar' added. On the cheaper side of non-sweet Cognacs is Marquis de Gensac.
These are not truths just opinions.

Taste is a very personal thing , I just do not like overly sweet drinks, N.M. Ferrand and that Armenian brandy are certainly in the category of sweet drinks. You interested in extremely complex Cognac ? Give Audry Memorial a try, you will not be able to drink anything sugary ever again.