Of the ones I've played...
Elden Ring
Sekiro
Armored Core 6
Dark Souls
Dark Souls 3
Bloodborne
Dark Souls 2
Just to be clear I think they're all great games (even DS2) so it's not that those towards the bottom are bad imo. Bloodborne is where it is solely because it has performance issues and the build variety is a bit lacking, and one of those can be fixed pretty easy with a re-release.
I actually enjoy DS3 more than DS1, but a notable part of that is the fanservice that wouldn't exist without the previous titles. In isolation, it coasts by with the best bosses in the Souls games while the levels and world design are probably at the bottom.
Sekiro and especially AC6 are difficult to compare to the Souls games due to the genre shift. AC6 just appeals to me and I hope we get more. Sekiro is
easily
the most polished game they've done in the last 15 years, everything just clicks together.
Ultimately, Elden Ring is like a melting pot of all the best parts of the rest of their games, but it still has its own identity rather than feeling like fanservice. The fact that it also has the best difficulty options and exploration also help quite a lot
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