Finding definitive texts about The Crusades is really tough. It's just too long of a time period and the massive geographic spread complicates things beyond what is possible for a singular narrative.

I've found that I reference Jonathan Riley-Smith's Oxford Illustrated History of the Crusades more than anything else. (For the record, they really shouldn't include "illustrated" in the title. It makes it seem like it's something it's not. There are just a few photos in addition to the text. That's it.)

What Riley-Smith does in this work really well is that he doesn't construct a singular, linear narrative. Instead, he curates really impressive chapters on a variety of subjects within the field. Reading it will give you vignettes that you can piece together yourself. If you want a rich, academic picture, he's your guy.

While there is a lot of controversial popular history on the Crusades that make finding a good academic work on the subject difficult there is a lot of very good academic discussion of the period. The Crusades is a huge topic and as a result it is hard for there to be one single definitive work on the subject, especially as new research is constantly improving our understanding of the Crusades and the people who participated in them.

/u/ombudsmen has already pointed out Riley-Smith as a great source for Crusading history. I often find myself recommending Thomas Asbridge a bit more then Riley-Smith but that is pretty much entirely down to personal preference. They have both written good broad treatments of the Crusading period.

For more specialist topics I would recommend the following:

Richard Barber's The New Knighthood is one of the best works on the Knight's Templar out there. He also wrote a very well known book on the trial and execution of the order called Trial of the Templars. More recently he's written a book on the Crusader States that I haven't read yet but looks to be very good.

John France is generally regarded as the expert on the military aspects of the Crusades, he's written a few books on the topic.

Anne Marie Edde's biography Saladin is a great source on both the Sultan and on Islmaic politics from the second through third crusades.

There does appear to be a bit of a scholarly divide between people who study the early Crusades (I-III) and those who study the Crusades after the fall of Jerusalem. I tend to read more in the former category so I don't know as much about specialist texts dealing with later Crusades. Jonatahn Phillips appears to have written some well respected books on some of the more neglected Crusades (II and IV) but I haven't read any of them yet, unfortunately.

I'm not aware of any books exclusively dealing with the Proto-Crusades. Someone in my university just wrote his Thesis on the subject but that was only this past year and I don't think he's published anything yet. There are definitely books on the subject of the later Crusades but I'm not particularly familiar with them, unfortunately.

I quite like Armin Malouf's The Crusades Through Arab Eyes and it seems to be generally well regarded (I know at least a few college course reading lists include it). It's not exactly a serious academic work, and it does not really claim to be, but it is a great introductory text. Malouf draws heavily from contemporary Muslim chroniclers and authors to draw his narrative and overall handles the subject quite well. It's never going to be the definitive work on Muslim attitudes to the Crusades but it is very approachable and a good starting point for learning about the Muslim primary source material.

The main text for my bachelor's Crusades class was "Sacred Violence: The European Crusades to the Middle East, 1095-1396". Its a narrative history, and attempts to address the topic from multiple viewpoints. Might be worth your time.