Ha ha, I like such lists. So…
1. Baldur’s Gate 2 (with SCS…)
Sorry for that, it’s a quite banal answer but… I think it is the best cRPG ever created. To be honest: none element of this game is truly great, but all of them are reliable what makes a truly good final product. Nothing is brilliant but everything is ok. It is long, hand-crafted game, with many elements to play with. I also think the party-gathering aspect of the game is the best in the genre. I very like most of our companions: they are interesting but not bizarre (as in, for example, Mask of Betrayer). The battle engine is great.
But the better answer will be: Baldur’s Gate Trilogy (with SCS). It is such a massive game with good dungeons (Durlag’s Tower…) and great, slow character progression. I like the atmosphere and story of BG1 more than BG2 and I prefer Baldur’s Gate city to Athkatla.
2. Might and Magic 3: Islands of Terra
It is my favorite blober. I like the exploration, riddles, puzzles and the whole atmosphere of the game. It is the most lovely computer fairytale. I like it a bit more then World of Xeen (but only a bit).
3. Mod for Mount and Blade: The Last Days of the Third Age.
Because it is the best computer adaptation of Tolkien’s world. And, for me, the single best M&B game. It has a lot of charm, and the game-rules are more interesting than any other M&B module (we have some goal and we can actually win the game…)
4. Witcher 1
Because something from my Country has to survive. And this is the only good game in the Witcher series.
5. Gothic 2
Because it is the best action-rpg with semi-open world. It is also, along with G1, the only video game which my wife likes.
Bonus Gold Box title:
Dead Knights of Krynn.
In my opinion the Krynn saga is better then the Forgotten Realms one. The world is better, more focused (FR is such a trash without any atmosphere). The character creation and progression is more advanced (better race/level restrictions table, sub-races, more classes, clerical confessions, moon-based wizardry). The interface is more user-friendly. Battles and encounters are, for me, more interesting (there is, in general, fewer numbers of monsters in groups, but they are stronger, with more skills and features). I like Champions of Krynn, but DKoK is longer, more open-world game.