Sekiro is far and away the best. The combat, for me, was so much more engaging than the rest of FromSoft's games - or the clones they inspired - that I actually have had trouble going back them. For example, I started playing Bloodborne for the first time, with a friend of mine who'd been wanting me to play it for years, and assured me it was the best FromSoft to date...we got maybe 6 hours in before we both decided we actually weren't feeling it. Again, I have to stress that he was telling me, as we were playing Sekiro, that Bloodborne is still his favorite FromSoft title, and that I would love it, because it encourages a certain level of aggression, just as Sekiro does. Going back though, ultimately, he was underwhelmed, and I honestly felt relieved when he said so, because I quickly got to the point where I felt I was only playing it for him.
I know that kinda sounds like I'm ripping Bloodborne, but that's really not my intent here, because I feel strongly that I would have this same reaction if I went back and played the first Dark Souls, which I LOVED, and would have previously given the crown for the best of these games. There's just something about the relentless rhythm of Sekiro, with the sort of anti-stamina, instead of the normal stamina bar in the other games. You're always on the assault, always in the enemies face, always clashing (as opposed to rolling around contact). It looks, and feels satisfying in a way that the rest of these games simply don't.