The core saga from the Spartan program to Zeta Halo. Play the games in this order and read the books where they fall. Every book title links straight to BookBeat.
Get the 2010 revised edition of The Fall of Reach. It was updated to match the Reach game.
Halo 5: Guardians is Xbox only. Everything from Reach through Halo 4 is in The Master Chief Collection on PC and Xbox, and Halo Infinite is on both.
Empty Throne overlaps Infinite's timeframe. Read it after you finish the game so it does not spoil the campaign.