For me, it's probably a toss up between Sekiro and Bloodborne. I've finished the games in their entirety probably around 4-6 times - either for their respective endings, just for fun, or trying to do a challenge run, like a BL4 Bloodborne run. Lies of P follows them closely at around 4 and soon 5 once the DLC rolls around.
Bloodborne and Sekiro were my first two soulslikes, and once it clicked, I was obsessed with both. I got platinums, watched video essays, listened to the OSTs all the time. They're very near and dear to me.
What is your most-played soulslike?
Definitely DS2, I didn't play Bloodborne(fuck you Sony) so I can't judge but with all the other soulslike DS2 has more replayability.
You have tons of routes from Majula to go, can skip some bosses/areas, fight the same boss multiple times with bonfire aesthetic to skip a good chunk of the game or use it to farm souls, with the alternatives form of healing you don't need to upgrade the estus flask so much. You had some bizarre mechanics like the spices to reduce spell/miracle requirements so you can use it even in a LVL1 Deprived build.
A true scholar! <3