Probably Deus Ex. And... I've played Fallout/Star control2/Baldur's Gate/PlanescapeTorment...blahblahblah
try this game, it has a great rgp game story: Beneath a Steel Sky http://www.revolution.co.uk/_display.php?id=16
Those Revolution Pont N Click games look fun. How would you say they compare to Myst or King's Quest? Have you played Trapped the White Rabbit? It's kewl, but it's scary. The squel, The Dark, is better, and still scary. They have a third one about advertising in space. http://trapped.rodrigoroesler.com/
I never really understood the need for a storyline. After all, we just want to blast things. Specially with a flight sim, I just want to fly and shoot, why did they include a stupid story in Ace Combat 6??? But to answer your question: Mass Effect very detailed, complex storyline...
I don't know Mass Effect. Deus Ex had a storyline that I thought was a bit of a mishmash of hokey conspiracy theories (including the UN police force that had free rein to run all over the U.S...a la the one world government consiracy theorists). It was definitely entertaining to play, but the story had some eye-rolling moments for me. I'd probably lean towards KOTOR, though I might be biased by the Star Wars theme and the fact that I deeply expected it to suck.
The original was better since you had a "fresh" storyline, the second pretty much assumes you've played the first and doesn't contain the twists of the first. It would actually make sense if they just rebuild the original, kept the storyline but updated graphics, physics, added some extras etc.
FF7 all the way, i think it introduced a lot of things and had action, drama, and comedy all in one. Planescape: torment was incredible too.
the Avatar series was pritty good, actually it was one of my favorites concidering it was created from scratch and didnt relie on other work like the star wars ones and the D&D ones do
I have only ever played the final fantasy series, I thought they were pretty good, FF7 was my fav with cloud. but i liked FF10 aswell because I liked the character Auron I thought he was cool. peace.