Well, that's you, for me it's the opposite again, not only when it comes to bosses, also the music in Nioh is way better in my opinion, the soundtracks of Fromsoftware games have no chance against Nioh's, specially Nioh 2, and I'm a musician so I know what I'm talking about. Yugo Kanno is a very well known composer and he did a hell of a job in both Nioh games.

In terms of enemy design and levels there is no contest, I agree, but that's Nioh is far better because it's real japanese history and mythology, while souls is just a fantasy made up by a studio, there is no chance for souls or sekiro here either compared to Nioh. Also the levels are better designed and thought when it comes to save points placements and shortcuts.

I think Sekiro might have better graphics if you like realism, but that's also subjective, I personally prefer Nioh's too.

I can understand people who grew up playing souls to have a special love to that series but let's be serious, Nioh is a more advanced game in every aspect.