I like them both the same.

I have to go with the one for the PS1. Twin Snakes added some great features but the voice acting really brought the game down. The subdued nature of the charaters voices of the Twin Snakes just didn't seem right.

MGS1 is how it really happened.

Twin Snakes is how it's told in the legend.

The Twin Snakes. There really isn't any good argument to say the original is better overall once you take off your nostalgia goggles.

Twin Snakes had MUCH better voice acting. They got rid of Mei Ling's accent which should never have existed in the first place and all the voice actors in general had matured their talents more for the remake.

Graphics is an obvious plus for Twin Snakes.

Overall, gameplay is probably better in Twin Snakes despite the fact that the first person shooting broke much of the challenge in the game. Particularly with the Ocelot and 2nd Raven fights. The new gameplay elements, weapons, means of killing enemies, means of completing objectives, and the added replay incentive of collecting dogtags compensate for the lowered difficulty.

Music is better in the original.

Storyline is better in Twin Snakes. Much of the localized corrections made in the original were removed and better translated from the original Japanese script. The over-the-top cutscenes weren't any more ridiculous than many of the stunts in MGS3 and all the new cutscenes in Twin Snakes were hand-picked by Kojima himself.

In Twin Snakes, Snake pulled his gun on the DARPA chief for no reasoh, drop-kicked Metal Gear Rex, and he stepped on a fucking missle.

thats called the WTF moment