I wasn't that much interested in Sekiro at first, mostly because of the fixed protagonist and narrower perspective in general, that's why I didn't buy it at lauch and only got around playing it much later.
After having played it some months ago I can say that Sekiro is an amazing game, combat was great and watching the difference in how effective you could become after having learned how to play well was quite the experience; the game, despite being "smaller", felt good paced and nicely tuned, a must play for me.
I find it hard to say which FROM game of this generation is the best, they are all great despite each one of them having some shortcomings.
DS3 I feel is probably the best one of the bunch, great replayable value, bigger world and much more content (especially with DLCs), the only problem I find in it is that it doesn't feel fresh enough compared to the other games and rethreads too much on DS1 legacy and not only just from an aesthetic perspective; despite that it is, probably, still the best Souls experience overall for me.
BB is amazing and started the gen with a bang, truly the first game that made having a PS4 a must.
The whole setting is great and many of the bosses are memorable, what it lacks is in its character builds which, despite the many different weapons, feel very samey in the end.
BB, In a way, feels like the middle intermediate game between DS and Sekiro, both in scope and gameplay in general.
DS2 is a great game and I'd say that it deserves to be played and completed at least once by any Souls fan but I wouldn't say that it is better tha any From game of the last generation.
The game is vast, massive I'd say, and has amazing build potentials both for pvp and pve orientations but level/enemy design is weaker compared to the other games (even its predecessors) and the bosses, outside of DLCs ones, are not memorable or that fun to fight.
Adding to that the changes in physics and the weird pacing in general and you end up with a game that, despite the huge amount of content, feels "off", feeling more like "the best Souls-like" game than "one of the family".