It depends what sort of a Whisky drinker you are.
If you buy to a budget and expect an interesting, quality drink for your money; You currently enjoy Glenfiddich 12, Highland Park 12, Aberlour 12, Johnnie Walker Black label or Grouse or even an Old Pultney 12 or if you are U.S. based and enjoy Makers Mark, Buffalo Trace or Woodford Reserve, you are all probably going to enjoy the VS cognacs from the big 4 houses; Hennessy, Martell, Courvoisier and Remy Martin. All of these are different but interesting drinks and all well priced and good enough to tempt you to venture onwards into VSOP or even XO territory.
If you enjoy the slightly older complex fruity, fragrant Speysides like Glenfiddich, Miltonduff, An Cnoc or Glenlivet you will love the equivalent light fragrant Cognacs particularly the VSOP expressions from Courvoisier. If you drink the 18s or 21 from these distilleries the Courvoisier XO may be perfect for you or Hennessy Fine Cognac.
If you like the more powerful deeper older style Speysides or Highlanders like Glengoyne 21, Tamdhu Cask Strength, GlenDronach, Macallan or Ben Riach you will find your spiritual Cognac home in Martell and Hennessy XO expressions.
Now if you are a real whisky geek who looks for tradition Non-Chill-Filtered natural colour and nothing added you are going to eventually be disillusioned. Initially, Cognac’s marketing of age, craft and tradition is beguiling but soon you will discover Cognac allows additives and all the quality Houses use them to a greater or lesser extent, it is just a part of Cognac, A150 caramel colouring sugar syrup and Boisé, a soup made from boiling up wood chips to give wood notes and character especially to younger expressions. Some houses take pride in the quality of their Boisé. Most are quite secretive about how they arrive at their final products but there is no doubting the years of experience and skill of the Cellar Masters and Master Blenders.
If you like high ABV and single Cask Whisky you won’t find many cognac equivalents. Most cognac retails at 40% ABV. They are blended the best with around 100 different eau-de-vie, some even more. The oldest of these up to 70 years old. Now no affordable whisky can make that claim. Cognac also now produces vintage cognacs and Hors d’Age (without age) – so generally much older constituents in the blend.
Generally, bourbon drinkers will recognise and enjoy the vanilla caramel and spice notes which come from the new oak barrels which are toasted. I say new oak but the barrel wood is more than 100 years old. If a bourbon drinker enjoys cognac they will love the increased variety compared to the core bourbon ranges. Cognac houses all make different tasting expressions, no two expressions tasting the same. There are an interesting array of small family independents making interesting and enjoyable ‘craft’ alternatives to sip your way through.

image courtesy of Martell
VSOP cognacs also offer an interesting alternative. A while back I was part of an excellent tweet tasting of some smaller house cognacs. Every cognac we tasted was well received by the experienced whisky blogger tasting panel. The favourite was Maxime Trijol a smaller family owned House. Interestingly the majority of testers preferred their VSOP to their XO although the tasters were split. In my own recent tasting of the core Martell range, The XO was superb and the VSOP was interesting, a cognac I must revisit. Of course given the high pricing of the XO range finding a good VSOP is a must. There are lower priced XO expressions from some smaller craft houses but not all deliver the quality of the big 4 XO’s. Like Whisky, age is not everything and with Cognac, the price is certainly not a reflection of quality. Sip around for an interesting journey.
For Single malt fans, Cognac provides a change. Something enjoyable and different. My personal taste leads me to the dark rather broody Cognacs and particularly Martell the oldest Cognac House. I enjoy the fact that the Cordon Bleu XO is the same cognac as that enjoyed at George V ’s coronation bash in 1911 and the same as was drunk on the Queen Mary’s maiden voyage in the 1930’s. I also love the depth of flavour and body. Hennessy XO a blend of over 100 Eau-de-vie provides everything I look for in a super premium spirit.
These are premium spirits and like whisk(e)y and rum at their best offer superb sipping spirits. Investigate these and they offer an intriguing and interesting journey.