I really liked Bloodborne, but I certainly wouldn't call it the best Souls game. To an extent it's a matter of emphasis, though: Bloodborne's faster, more aggressive pace and the interesting trick weapon mechanic work well for the boss battles, which are the highlight of the game, and arguably better than in other Souls games. I found the boss fights (well, the ones in the Old Hunters) more difficult than the other Souls games, and I felt like I really had to delve into the nitty-gritty details of how different trick weapons worked to deal with each boss; for instance, the small form of Beasthunter Saif has a really neat quick lunge on R1 that was essential for killing the Orphan of Kos while a bit underleveled. Dark Souls has more variety, but overall a lot of the details don't matter so much because the boss fights aren't as technical.
That said, I don't think that boss fights are the central element of Souls games, since you spend most of your time going through the levels instead, and in this area (which, to be plain, I consider the most important area) Dark Souls is clearly the best of the Souls games. And so:
And in environment variety, Bloodborne wins , you go to a Dark victorian city during inquisition to a Castle hidden to campains inhabited by lovecraftian monsters to a church surrounded by a singing monsters choir celebrating litterally Cthultu to a surnatural place full of crazy demons to the center of city of Yarhnam surrounder by multiples invisible gods which can only be seen by madness creatures to etc...
What Dark Souls does, and Bloodborne largely doesn't, is give its areas variety not only aesthetically, but
mechanically. In Dark Souls, you're more likely to die falling of a cliff than by the enemies of each area, and so various enemy encounters are more strategic, since you have to figure out how to engage them in light of whatever natural hazards present in each area. These escalate as you get further into the game, in a manner that differentiates each area: The Undead Burgh is quite tame, but lead to the disorienting Depths with its narrow spaces and pitfalls to lower levels. Blighttown has large but precarious spaces, with the poison blowdarts forcing the player to keep moving and avoid blocking, and the incredibly annoying mosquitoes. Sen's Fortress is full of traps, the Catacombs have respawning enemies, Tomb of the Giants is dark and full of falls, New Londo has ghosts and water, the Crystal Cave has invisible bridges (admittedly kind of silly), the Demon Ruins have lava and Lost Izalith has dinosaur butts. The Great Hollow is essentially a climbing challenge. Each area being different, the player is incentivised to gear differently to deal with the circumstances, since the game
does in fact contain stuff that can mitigate the challenges in each area if you have it. The Metroidvania-ish, half-open nature of the game world means you might do things in different orders and different equipment, making things harder, easier or just plain different for yourself.
My point, I suppose, is that an interesting encounter is the sum of the environment and its enemies. Dark Souls II's best area is the Shrine of Amana, because it's the one where the environment has the biggest impact on how you have to approach the encounters, and this is something Bloodborne mostly lacks. Bloodborne's areas are
decent, but ultimately they don't have the same escalation of danger; there are few significant hazards that would impact the gameplay (the Astral Clocktower
is great, and I guess the Nightmare of Mensis counts), and so, the game is mostly just about fighting the mobs in each area, which too have less variety than Dark Souls' enemies, on the whole. The trick weapons are great, but the encounters are pretty samey and unlike boss battles, they don't really call for much strategy or experimentation, and in any case you don't have the equipment variety to really approach situations in significantly different ways. Bloodborne's areas look great, and searching for the secrets and shortcuts is fun enough, but ultimately they're pretty formulaic, structurally, and so the game doesn't quite have the sense of wonder and danger that makes Dark Souls so delectable.
Which, I suppose, is the crucial question for Elden Ring (that is what this thread is about, right?):
how do you make a bigger, "open" world with the same character as Dark Souls' obviously handcrafted world and environments? It's not obvious that it can be done, but then again, maybe it's not going to be an "open world" the way the term is commonly used at all.