Voted Demon's = Dark = Dark 2
Because I just can't pick a favourite. All three games have their strengths and weaknesses. Demon's Souls still has the best PvP for me, despite the lag. Dark Souls improved the PvE over Demon's by almost every aspect, though. Dark Souls 2 has the worst PvP netcode of the three, and in some cases the hitboxes are the worst too (though in other cases they are very good indeed, I was amazed to see a giant knight's sword swing over my head while my character was crouched for Firestorm... but we've all seen those mimic gifs and Smelter and Pursuer gifs, too, gah), and it's not as interconnected as Dark Souls, but the sheer volume and scope of the game is impressive, not to mention the shitton of secrets and amazing diversity of weapons and gear. I really like the torch mechanic too, I wish it had been used even more, but it really added something to levels like the Gutter and Shrine of Amana. And No Man's Wharf and Lost Bastille are probably my favourite levels of all Souls games...
... after Tower of Latria. Now that one is still unparalleled in terms of atmosphere and level design. 3-1 especially, with the moaning of prisoners, the bells of the mindflayers, the decrepit prison... dark gothic fantasy at its very best. And I had so much fun with the organized PvP, it's just too unbalanced and broken in Dark Souls in comparison (lolpvp is still fun, but I can't ever take it remotely seriously).
...Ok, I lied. My favourite level of all the games is the Painted World of Ariamis. I just love that Legacy of Kain-like atmosphere and the level design is nothing short of perfect. I believe it was pretty much their vertical slice, which makes sense.
Also, Dark Souls probably had the best bosses, and the most original art style in terms of architecture and monster design. Dark Souls 2 has some great ones but there are too many "that's it...?" pushovers. Artorias, Kalameet and Manus are probably the best bosses in the entire series and they're all in the DLC, hah. An aspect of Dark Souls 2 that wins over the other games is the diversity of playstyles and roleplaying. All the games have this, but I thought DkS2 did it even better. It's really fun to experiment and discover what works and what doesn't, how a build is so good it's broken in some places and pretty weak in others, and so on (I wrote a long post about how bad
and good dual wielding whips can be in the OT... that was a lot of fun to play around with!).
Sorry if this is a bit of a stream of consciousness kind of mess. But tl;dr: all the games are awesome, and I can't pick one over the other. If they made a Souls game that stripped all the flaws from the previous games and reinforced all their strengths, it would be GOAT for sure. As it is, well, the series is GOAT for me but it still could be even better.
