I can only include things I’ve actually read.

Darth Bane trilogy (anything prior is ancient history that is inherently dubious, and there’s a few things that dovetail real nicely with TROS, almost enough to feel like they’re good bookends)
Darth Plagueis
Master and Apprentice
Cloak of Deception
TPM
Rogue Planet
The Approaching Storm
AOTC
Misc pre-2008 Clone Wars books
The Clone Wars Microseries
Labyrinth of Evil (including any contradictions between this and the Microseries; discontinuity is good for you)
ROTS
The Han Solo Trilogy (fudging any PT continuity issues)
Rogue One, and it’s prequel tie-in novel
ANH
Splinter of the Mind’s Eye
ESB
Shadows of the Empire
ROTJ
Bloodlines
TFA
TLJ
TROS