This entire thread has a
quality to it.
The fact is that there are a variety of reasons to like an adventure game (novelty, puzzle quality, art, story, smooth gameplay, historical importance, etc.). For instance, Grim Fandango looks and sounds great and has a great story, but in my opinion the puzzles are mediocre and the pacing is not particularly good for an adventure game -- way too much dialogue relative to non-dialogue. (The controls were not good at launch, but they have since been replaced if you get the remastered version.) Full Throttle has one of the few well-done protagonists who is not a scavenger/nerd type, it looks and sounds great, and it has generally smooth gameplay, but the puzzles are very easy and the game is very short. The first two Kyrandia games, particularly the second, have spectacular art and they're quite large, but the setting is generic, the story is so-so, the puzzles are frustrating, and the gameplay has a lot of friction (
i.e., you can expect to get stuck for all sorts of reasons). They are also relatively unimportant as historical significance goes in comparison to Sierra and Lucas Arts games of the same era.
Recommending Technobabylon (on which I gave some story/puzzle advice), Primordia (which I made), or Quest for Infamy (which I backed on Kickstarter and greatly admire) is absurd -- none of those are "old" and non are comparable to many games that
Makabb hasn't played. In my opinion, even games like Torin's Passage or Syberia are ridiculous.
I'd propose something like:
FIRST: Quest for Glory VGA. (I don't think you'll be able to get into the EGA version today.) Probably my favorite adventure game and certainly my favorite on that you haven't yet played. If you like it, by all means continue with the series.
SECOND: Indiana Jones and the Fate of Atlantis, another tip-top game. Better than the Search for the Holy Grail.
THIRD: The Sierra VGA era greats (King's Quest V, King's Quest VI, Space Quest IV, Gabriel Knight) and the Lucas greats (Loom, DOTT, Sam & Max Hit the Road, Grim Fandango).
FOURTH: The smaller-developer classics (Simon the Sorcerer, Kyrandia, Broken Sword, Discworld Noir).
FIFTH: The "deviate from standard" classics (Last Express, Sanitarium, Gobliiins, Tex Murphy, etc.).
But honestly, it all depends on what you like. If it turns out that you like low-difficulty, low-stress story-oriented games, or dislike the traditional look and feel, then I'd rejigger things. Still, QFG VGA is an easy place to start.