Which game's storyline is best?

Homeworld, Day of the Tentacle, Waking Mars, Thief I & II, No One Lives Forever, Betrayal at Krondor, Okami

mass effect,bioshock and Bioshock infinite, to the moon, indigo prophecy

The Walking Dead, Mass Effect series (minus the last five to ten minutes of ME3, of course...Yes, I'm still angry about it) and Planescape: Torment.

Final Fantasy Tactics (the original PS1 version) had one of the best stories I've ever seen in a video game.

Star Wars : Knight of the Old Republic I (the RPG one not the MMO one)

and Final Fantasy IV

also Call of Juarez : Bound in Blood, then Call of Jaurez 1 (play in this order instead of releashing order)

Bioshock, Bioshock Infinite, Dragon Age series, Crysis series

Plants VS Zombies :D
LOL
But I really liked the plot in GTA IV and Prototype.

Baldur's Gate 1&2, both Icewind Dales, Planescape Torment, Sacrifice, Arcanum, Neverwinter Nights, both KOTOR games(haters gonna hate), Legacy of Kain series, VTM Bloodlines. The only "modern" game i've played that even came close to these was Dragon Age Origins.

Silent Hill 2>>>>

Portal series :)

You can't choose the best, that's like asking: "what is better, chocolate or fries?"

Thomas Was Alone.

The Walking Dead OR Bioshock series :)

-Warcraft 3
-Half life series
-Kotor
-Nexus the jupiter incident

This http://www.youtube.com/watch?v=E_SEQJHHmvg !

-The Walking Dead

-Half Life series

-Fallout 3

-Portal series

-Call of juarez Gunslinger

-Metro 2033

-Metal Gear Solid series

I could think up a huge list but I'll try to keep it short:

The Walking Dead, Thomas Was Alone, To The Moon, Heavy Rain, Indigo Prophecy... I'm just gonna stop because there are dozens of games more and a lot of them are mentioned in here anyway! :p

Last of Us ♥♥

Final Fantasy VII & X
Bioshock & Bioshock Infinite
Tex Murphy Under a Killing Moon, Pandora Directive, Overseer

If it has not already been mentioned, I would like to suggest To The Moon. A short, simple RPG style game where you explore a person's memories as they near death. Very insightful and emotional.

Portal Series
Call Of Duty MW Series
Assassins Creed Series
Batman Series
Half life Series

Final Fantasy X, Super Robot Wars Original Generation 2,

No such thing as "best" story. But Ocarina of Time is still my favorite. Also Darksiders and Bioshock games.

Mostly RPGs like Dragon Age, Mass Effect, The Witcher. Some FPS' got amazing stories too like BioShock, Half-Life.

Pacman obviously