Pick 3.
Boxed sets/ Accessories
My all-time favourite is Castles Forlorn boxed set (also for sentimental reasons since it was the first Ravenloft product I bought after the Ral Partha Denizens of Darkness minature box set, I was in the modeling hobbie before playing AD&D). I still remember reading the darklords tragic story many times at night, and love the Goblyn culture.
Then the Gazetteer series was really good, I liked the "historical" info in them and description of the various cultures. I have to say I am between Gazetteer I (with the fleshing out of Hazlan, Kartakass realy good adaptation of Forlorn and of course Barovia) and Gazetteer IV: Borca (nicely done), Invidia (had already been detailed in Evil Eye), Verbrek (at last some info), Valachan (nice inclusions of the Dungeon Magazine adventures), and Sithicus (some really useful info on the changes of the domain). But Number 1 wins cause there is not one single information I 've found there that I don't like. Love the Terg history it fleshes out the domain a lot having more information on it's past and I like the false? connection between the Tergs and Gundarakites. The stories of Kartakass grandfather wolf story suits the domain as well as all the information given. Hazlan at last is described thoroughly and like the whole Eastern/ Ottoman design of the domain with its many aberration mysteries. Forlorn one of my all time favourite boxed sets gets a very good adaptation like the information on it's forests and the way the darklords story is being desribed by the druids, giving hints but not too much. And they continued the local character development in a very creative way compared with Domains of Dread which set the base for this.
Last but not least I would say Realms of Terror Box set (it set everything in the setting I love, domains, darklords, great maps of the various houses of darklords, great images by Stephen Fabian) if it had the secret societies from Forbidden Lore it would have been a powerful combo.
Favourite adventures:
Evil Eye (it set a lot of "ground rules" of how a good adventure is being laid out, and the event's described changed the setting in a very creative way.
I6 Ravenloft (started everything no more comments)
Adam's Wrath (interesting senario were the PC's go around most notable places in the domain, I really like Adam's lair, though it had it's mistakes. Speaking of mistakes if Feast of Goblyns was a bit better written in some parts (especially the begining of the plot) it would have taken this place, competing with House on Gryphon Hill which is nicely laid as an idea but need serious reworking. I had wished previously that it would be rewritten for 5e but after VRGtR I' d rather not, who knows what could happen then maybe they would clone everyone as they did with Jander...

Normaly I would had placed Roots of Evil since I like the plot a lot but I didn't like the high fantasy lair of Azalin so much, so many things have no reason to be there. But I just love that jackal-headed demon and his frustration.
Favourite Novels:
I, Strahd. Memoirs of a Vampire (I really enjoyed Strahd's perspective)
Scholar of Decay (I really liked how the vanity of the darlord is portraid and the whole culture of the domain, on all levels of "society")
Spectre of the Black Rose ( I was an old time fan of

Favourite Dungeon adventures:
Cat of Felkovic (set some ground rules for Valachan though in the pictures the commoners are white and all the badies not, fortunatelly they set that mistake straight in later editions and we get to see Castle Pantara, plus a possible death of a darklord for those ignorant fools out there, who believe that all darklords are unbitable

Horror's Harvest (very interesting adventure, though lacking the authoritariarism of Falkovnia, but this makes it more interesting as since it is a clue that someyhing is off)
Fair Barovia from Dungeon Magazine #207 (reminiscent of the encounter with Leo in I,Strahd)

Favourite Dragon article:
Van Richten's Legacy: The Cult of Simon Audaire from Dragon Magazine #264. (very original)
The Life of Soth from Dragon Magazine #416 (very good article especially for those who haven't read the dragonlance campaign setting books or novels, has also the song that his entourage of banshees sing, though I don't know if it had appeared before. This is very useful as it can be changed as to show the forgetfulness or frustration of the darklord as he is reminded that he is not home.)
Domains of Dread: The Endless Road from Dungeon Magazine #174 (though this is a Dungeon magazine article it looks more like a Dragon Magazine article since there is no adventure there. The story of the Headless Horseman finally revealed and makes more sense now than just some horseman who lost his head and his spirit haunts the roads of Ravenloft as it was in the Darklord accessory. Probably the best article from Ravenloft 4e.
Land of Spectres from Dragon Magazine #258 goes with Ravenloft: The Shadows of Sithicus from Dragon Magazine #351 (the first describing the characters from Spectre of the Black Rose the other showing the changes later appearing in the Gazetteer series).
