So spekkio since you don't like adventure games at all, why do you torture yourself ? Is this list for purely collectible value ?
Anyway, I consider Syberia to be shit. Instead of doing any actual historical or even geographical research, hack designer Benoît Sokal makes up some imaginary places to fit his silly story and puts some "automaton" crap in the story so he can rationalize the fact that you constantly find locked doors on your path, where you have to solve some completely unrelated automaton puzzle riddled on them.
I also consider Still Life to be shit (some VERY stupid puzzles and the story is nothing much) while I find Post Mortem to be great despite its flaws.
IHNMAIMS is great.
Keeping GK 2&3 is a good idea.
The last crusade is good, not as good as fate, but good.
Keep only monkey Island 3, 4 isn't worth it.
You probably have adventure/rpg hybrids stashed elsewhere, but since these are more point and click adventures than RPG let me remind you of the:
Quest For Glory Series
Veil Of Darkness
Elvira Mistress of the dark
Other adventures I love:
Discworld : Excellent humor, really some of the best humor in adv games. Some nice ideas on puzzles, but VERY hard and at times convoluted.
Discworld Noir: Notable for its awesome atmosphere and story. Interrogation puzzles are interesting.
Maniac Mansion: Multiple Characters, multiple paths... for this game the SCUMM engine was created... this game stated it all for lucasarts... need I say more ?
Conquests Of The Longbow: SCO said it.
Freddy Pharkas - Frontier Pharmacist: Nice lulzy story, solving most puzzles by gathering materials and mixing them into various concotions.
Shadow Of The Comet: The only 2D adventure game that actually manages to create such a heavy, scary atmosphere.
The Lost Files Of Sherlock Holmes - The case of the serrated blade: This, in my humble opinion, is THE Sherlock Holmes game. (its sequel isn't bad either)
Police Quest and Space Quest series are also worth of attention, get at least PQ1 and Open Season and SQ4 & 5.
Dreamweb: Yeah, you know.
EDIT: And of course Leisure Suit Larry. 1, 5 and Love for sale are the best.
Now go back to reading Kotaku.