I’ve played every soulsborne-sekiro game. Here’s my personal take on BB vs DS3:
1. BB has a more unique gothic horror setting.
2. BB had ~15 weapons that were all super unique and balanced while DS3 had lots of weapons that were all kinda meh or same-y.
3. BB has no shields and combat is much faster paced.
4. BB has slightly better level design.

That being said:
1. DS3 has slightly better bosses.
My ranking for all of the games goes as follows:
1. Bloodborne
2. Dark Souls
3. Sekiro/Dark Souls 3
4. Demon’s Souls
5. Dark Souls 2
The setting is purely subjective so comparing them is pretty useless imo
DS3 has around 200 weapons with 20 different types, with many different combat arts, especially bosses weapons so that's still more than BB
DS3 offers more builds than BB (which only has 3)
I agree with BB having a better combat system and level design
DS3 has much better bosses, only memorable ones from BB are Gascoigne / Gherman / Maria / Ludw
ig / Kos while DS3 has Watchers / Sulyvahn / Champion Gundyr / Nameless King / Lorian & Lothric / Soul of Cinder / Gael / Friede / Midir
And also Estus system is way better than the Blood vials one, you don't need to grind for health in DS3
I would also add that BB’s soundtrack was done by a live orchestra while DS3’s wasn’t. Gehman and Ludwig’s themes are better than every theme in DS3 imo.
Also, this is only an issue if you’d played the other Souls games prior to DS3. But literally there’s so much re-hashing of previous stuff.