what i'm interested is in an 'everyday' cognac, as much as there can be an everyday something in a liquor category where the most basic of the basic costs $25 a bottle.
What about the Rémy Martin VSOP, in the frosted green bottle? It has some character, it's consistent in my experience, and it does wicked things with mushrooms or the odd anachronistic rich shellfish sauce (supplementing Sherry, Madeira, etc. [Note 1]). Also, for years it has run around $29 at the local Costco warehouse store, comparable to MacCallan 12 (a sound entry-level malt: one can do far worse in whiskys for that money).
I support Germain-Robin, its smaller neighbor Jepson, and other US artisanal products of my own native region but (a) the request was for Cognac (as in Charente river) and (b) the price is highly competitive.
(Myself I can't picture using any of these products in cocktails -- not from concern for the cocktail, but for the fine spirit, which risks being wasted. However te gustibus . . . )
I have zero vested interest in any of this. -- Max
Note 1: For instance. Take cleaned cultivated or (preferably) wild mushrooms of your choice. Cut as you like. Stir-fry hot and fast in a little butter, salting if you like. When they start to look cooked, add enough Sherry, Madeira etc. of your choice to sort of drown them, and cook off fast until almost dry. Watch carefully so they don't burn. Throw in some Cognac and (if you like) ignite, such as by tipping the skillet to the gas flame. After the flame dies out, finish with a little heavy cream to make a sauce, and adjust the salt. Serve over something bready as long as it's not a puff-pastry shell, I'm sorry, there are limits. If you really want to recreate 1971 grand-palace dining, borrow an oily headwaiter with temporary hairpiece and French accent, and an itchy palm. That is not necessary though.
Note 2: Steaks au poivre probably do better when sat to come up to room temp with freshly cracked peppercorns pressed into them; cooked hot and fast in a pan; and deglazed with Bourbon. Try it. (Save the cream for the mushrooms and the Maitres d'hôtel.)
PS: Katie got in here with good brief suggestions, as usual, while I was assembling this. Listen to her.