While you're active in this thread:
Are the light novels worth it?
And how canon are they? You can also give your personal opinion on which one's are worth reading and why, if you don't mind
There's only one set that's recognizes as canon and translated into english and that's Can't Fear Your Own World.
It's all based around Hisagi trying to determine some cryptic words Aizen gave him regarding Tosen, moments before being sealed up. Involves Arrancar, Shinigami and surviving Sternritter in a plot involving a new antagonist who was contemporaries with Shunsui and Ukitake and murdered Tosen's childhood friend.
IMO, CFYOW is really good and fills in a lot of the world building questions that TYBW left us in the dust for. We learn so much about the noble families, the Soul King and Fullbringers in this novel. I really do recommend it, I think it's cheap on VIZ and comes in three issues. And while the contents of CFYOW are canon, Kubo described them as soft canon. Everything happened by the literal interpretation of events isn't canonized. So a little useless for most powerscaling, but you can easily say Urahara fought off this Aizen level Fullbringer.
The other novels I've never fully read because they never got put out in english. I know they aren't really regarded in the same way as CFYOW. Some elements of them are consistent with the manga and I do feel like Kubo keeps some aspects of these novels close to canon. I know Spirits are Forever With You (the Azashiro novel) is probably closest to canon due to Kubo incorporating elements from it.