Demon's Souls > Nioh > Bloodborne > Dark Souls > Dark Souls 2 > Lords of the Fallen
Demon's Souls and Nioh both are masterpieces. Both are extraordinary.
Demon's Souls is still my favorite, every bit of it makes you feel like you ain't shit, and nothing feels like putting a shield up and just surviving attacks on that game... the pressure, the atmosphere, the music, everything...
Nioh was a dream come true and have BY FAR the best gameplay from any of the those I played. It's stunningly charming, interesting and challenging. The 2x1 fights in the end of the game are priceless. I can't make it justice, go play it.
Bloodborne is almost there, but the random chalice dungeons and lack of cool armor/shield made it drop a bit.
Dark Souls is a great game too, with the best level design, but it was not that enjoyable to play as the others.
Dark Souls 2 is actually more fun to play than 1, and it's also a great game, but it was far too easy overall (Darklurker tho).
Lords of the Fallen had such cool looking gear, but was nowhere near as interesting in any other aspect compared to the others.