So I have a ton of B&N gift cards sitting around gathering dust. I decided I am going to spend it on Halo books and I wanted to hear from people what some of their favorites Halo books are.
First Strike and Ghosts of Onyx remain my personal pre-343i favorites while the Forerunner trilogy are my 343 favorites.
For me personally, the best Bungie-era Halo novels are Ghosts of Onyx and The Cole Protocol. The rest (Fall of Reach, First Strike, Contact Harvest, The Flood) are all pretty good as well.
The 343-era books are much more of a mixed bag. My favorites there are Silentium and Broken Circle. The rest of the Forerunner Trilogy books are good as well. The whole Kilo-Five Trilogy (Glasslands, The Thursday War, Mortal Dictata), however, was a massive disaster.
Fall of Reach, First Strike, and Ghosts of Onyx are must-reads. If you’re interested in the Forerunners, then I would pick up Greg Bear’s Forerunner Saga. The third book is far and away the best IMO so prepare to struggle through the first two if you do that.
Halo Evolutions is actually a really good compilation of unconnected short stories from various authors that’s a really good starting point into the Halo extended universe I think. There’s lots of gems in there.
I still have to finish Contact Harvest…
I honestly loved Contact Harvest.
I really enjoyed how they had the Ungoy Deacons and Lighter than Some ( i thinks that the right one) perspectives.
The others i enjoyed were Silentium and Fall of Reach.
I’m yet to read The Broken Circle because my local book store doesn’t have it 
But they’re all great - The Flood isn’t that necessary - and Kilo Five Trilogy isn’t great - The rest are awesome.
I have only read The Fall of Reach First Strike and The Flood as well as Ghosts of Onyx. All are great books and I would def recommend them. Chiefs origin and the Halo CE story completely fleshed out. Ghosts of Onyx was just a darn good story.
I have the Cole protocol but havent read it.
Fall of Reach is my favorite. Goes to great lengths to set the stage for the Spartan program. Good foundation for moving forward.
I would suggest reading primordium, silentium and Cryptum. Altrough Halo books are excelent to explain the history surrouding eveything, The Forerunner saga does a very good job explaining the Flood and the Forerunners.