I like the history section about the judo/jiu jitsu rivalry in Mastering Jujitsu, interesting stuff for sure.

I have a few martial arts books and bjj books but my two favorites have to be breathe and jiu jitsu university by Saulo Ribeiro

I got this old gem right here from Master Joe Moreira. Solid book about the guard.

I assume Ed Beneville did most of the work on that, but either way, those books were fantastic.

I have all three: one of the very few times I've successfully added a technique into my long term game purely from a book (shin in elbow trick, which was in Strategic Guard).