Honestly, you really can't go wrong with any of demons soul, Dark Souls, bloodborne, Sekiro, or Elden Ring. All are great in their own right (and leaps and bounds better than Lies of P, which I also enjoyed). Probably want to stay away from Dark souls 2 though to begin with. It's a very divisive game.
You don't need to play any of then in any order. There are continuing themes, especially in Dark Souls, but really no particular story continuity unless you want to dig super deep into YouTube theories.
I would personally start with Dark Souls 3. Elden Rings world is massive. Not a bad thing, it's one of its strengths, but it's a lot lol. The rest of the games have exploration and branching paths to a certain extent, but they are still fairly linear. DS3 is the most refined of the Dark Souls 3, DLC is very good too.
Edit. Also, I don't know the current state of Multi-player on Elden Ring. But if you were to wait until the DLC drops (sometime) there will be a ton of people playing again to help, invade, duel, etc. Something to consider.