I've never played Demon Souls and only recently discovered Dark Souls. I fell in love with this game during the prologue cut scene, which I still watch from time to time on youtube. Of course my first run was the most exciting as far as the unveiling of the story, but I just don't see how Demon's Souls could possibly top the lore and environment that Dark Souls sets up for the player. I also love that the events and details of the story are presented in a subtle way, and that the game doesn't put you through an hour of indoctrination like so many other RPGs. --- PSN: Nah-Mir
Better is subjective as they both depend on the player a bit to build the story. However, I will say I truly miss there being an intro cinematic in Dark Souls. To this day - every time I boot Demon's I watch the full intro movie. The atmosphere created in Demon's really does stand alone.
Well, I wouldn't plan on playing PvP anyway. I've also heard that Demon Souls doesn't have an open world, which is a huge deal breaker considering how beautiful Lordran is and how much fun it is to explore. --- PSN: Nah-Mir
EDIT: I'm not sure if you're currently playing through the game or have just finished it, so:
Because it has pretty cutscenes that explain, in no unclear terms, what has transpired in the land of Boletaria and what you need to do about it, and how it'll fix it. I.e. it just sets the story up better and in a more relevant time-frame to when the player plays the game. The fog is bad, it destroys the land, demon's devour the souls of men and turn them into mindless savages, etc.
In Dark Souls, you get told about what happened a few hundred years preceding the existence of your character. A bunch of dudes killed some dragons. And then you wake up in a cell. When you get to firelink, you're vaguely told to ring some bells. Then you're told to go find a lordvessel, and then you're told to go eat the souls of a few people so you can 'link the fire' and extend the age of flame. You're never really told why you're doing this other than answering to some call of being the 'chosen undead', or what the exact effect of linking the fire is or why it's a good thing. The only one who gives some meaningful exposition to an end-game choice is a serpent, explaining that the age of dark is the age of men, and that the Gods are actively trying to prevent an age where they are not dominant.
Chances are you won't meet Kaathe on your first playthrough though, so it just feels like a lot of meandering for little reason other than 'you're the chosen one'.
Demon's Souls - The Monumental's Story: http://www.youtube.com/watch?v=MKle6OeMgjs
Dark Souls - Intro Clip: http://www.youtube.com/watch?v=eLaCmCxb4tA
I'm going to say I like the lore & story of Dark Souls a lot more, I've watched all the lore vids, read the item descriptions, understood the big picture, etc. But on a first playthrough you're likely never going to put it all together. Neither game is particularly story based, but DeS did a better job of explaining why what you're doing is worth doing and why you should be doing it.
In Dark Souls, well some dudes killed the dragons after they got powerful. Why? Were the dragons evil? Did they rule with an iron first? Did they need to be destroyed? I'm a chosen undead? Why am I ringing bells? Why should I link the fire? What does extending the age of fire do? etc. It's easier to say why this stuff is meaningful after you've played the game multiple times and fine-combed for story details, but on a first run through the reasoning is flimsy and you don't know enough to be able to make the connections. --- | Xbox 360: Atrabilious/ClassiestFiddle/Phantom Ostrava | PS3: Jazzy_Bones | Rent my Dragon's Dogma pawns on my Xbox GT's.