Since the soulslike community is quite diverse, I can imagine many different opinions to emerge here. Curious to hear your thoughts!
I'd take Sekiro 2 any day of the week. Bloodborne 2 would be amazing, but Sekiro, to me, is the pinnacle of the genre and has so much untapped potential that's laying dormant. Bloodborne is too similar to your "standard" soulslike compared to Sekiro, even though I love Bloodborne as well.
Bloodborne 2, easy. I don't even really want most of these, let Dark Souls and Demon's Souls rest as franchises. I'd also prefer if FromSoftware returned to the more "metroidvania" style of open worlds as opposed to Elden Ring's "wide as an ocean, deep as a puddle" approach. It's really just between Sekiro 2 and Bloodborne 2 for me, but I can't actually see how FromSoft would meaningfully iterate on Sekiro's combat system. More of it would be good, sure, but a big part of my intitial enjoyment of Sekiro stemmed from learning the combat system for the first time. I can definitely see how modern FromSoft could really spice up trick weapons though, and probably improve on the magic system.