In addition to all the ones that other people hear already listed (mostly legends but quite a bit of cannon too) if you have been enjoying Andor there is a book called The Mask of Fear which came out before S2 which expands on key characters.
The Room with No Doors by Kate Orman
Return of the Living Dad by Kate Orman
Human Nature by Paul Cornell
The Also People by Ben Aaronovich
Bad Therapy by Matt Jones
I mean a coworker said the same when I loaned him the first EU novel. But the new canon book is worth a read. It’s yours if you want it, foc of course!
I may be an outlier but Kevin J. Anderson’s Jedi Academy Trilogy is superior to the Thrawn trilogy, and his novel Darksaber has the coolest moment from the EU/Legends canon
I'm a *huge* fan of the Thrawn trilogy (Heir to the empire, Dark force rising, The last command) and the follow up duology (Specter of the past, Vision of the future) - I can read those over and over and over again
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Also Rogue Squadron books by Michael A Stackpole (Rogue Squadron, Wedge's Gamble, The Krytos Trap and The Bacta War)
Then Wraith Squadron too.
I, Jedi
Shadows of Mindor
Hand of Thrawn Duology
Allegiance
Kenobi
Shatterpoint
Return of the Living Dad by Kate Orman
Human Nature by Paul Cornell
The Also People by Ben Aaronovich
Bad Therapy by Matt Jones
Plagueis
Tarkin
Darth Plagueis
Darth Bane Trilogy
Shatterpoint
Master and Apprentice
Dark Disciple
Reign of the Empire
Catalyst
Lost Stars
Bloodline