A really good book (not really theory, but it might help you learn how to sight read) if you are interested in heaps of Genres is the Berklee "A Modern Method For Guitar", simply because you learn to play music that isn't of any particular genre, but rather how chords can come together to create good music. There's no particular style to the music you learn, it is just a good solid base on basic melodies, etc. Of course, it does get very challenging very quickly, Book 1 starts off for beginners but I am not very far into it as it is still really good for more experienced players. Sorry if this sounds like a plug.