What is the most entertaining, insightful, and least abstruse text by Aleister Crowley?

Well, like you I am also interested in learning about Crowley. He does seem quite brilliant. I think his "Book of the Law" might be a good one considering it was autowritten by his Holy Guardian Angel and contains the foundations of Thelema. Other than that I am not so sure, considering he wrote a lot, but I hope you get some better answers.

Actually I was just listening to a lecture (L.Ron Hubbard 5th Dec 1952) and he said while talking about our ability to create as it relates to magic ....

" A magician- the magic cults of the eighth, ninth,tenth,eleventh and twelth centuries in the Middle East were fascinating. The only modern work that has anything to do with them is a trifle wild in spots, but it's a fascinating work in itself and that's work written by Aleister Crowley, the late Aleister Crowley, my very good friend. And he did himself a splendid piece of aesthetics built around those magic cults.It's very interesting reading to get ahold of a copy of a book-quite rare, but it can be obtained "The Master Therion" by Aleister Crowley."

Haven't read any of his books myself but maybe this is helpful.

Asking this question is like asking which one food should I eat at a buffet? Crowley was a prolific writer and there really isn't one book of his you should read over any other. He wrote fiction and nonfiction so take your pick and start reading. Keep in mind, he loved playing tricks and practical jokes on his students and readers and deliberately included misinformation in his work.

Just got to the store and see the one that seem the most interesting to you.(that's what i do when i have a problem deciding wich book to pick)

The bit that says:

A is A, therefore: A