To be honest, i kind of prefer Demon's Souls. It feels more structured with the Nexus as the hub, and so you always have an idea of a tangible goal to work towards - pick a world, progress to the midway / end boss, return to the Nexus, move on to the next world. The Nexus also always felt like a safe haven to retreat to so you can focus on your stats and equipment without worrying about monsters or other players, as well as interact with NPCs to learn new abilities or just have a chat. I like the ambition of Dark Souls' open world, but i prefer the structured nature of Demon's Souls. Demon's Souls is also more forgiving if you pick a caster character, particularly the Royalty class who starts out with a ring that replenishes MP over time. That class was basically easy street in dealing with anyone who invaded as a black phantom, as well as being able to pewpew otherwise monstrous bosses from afar. Magic got nerfed in Dark Souls in light of this fact.