This is the first book I began using to teach students Zentangle, appropriately titled Zentangle by Jane Marbaix. If you click the link you will see it is very affordable as its an older book now.
This is the most recent book I have purchased on Zentangle and I like the format of the book a lot better. Since I mostly teach individual tangles and this book is laid out with one tangle per page it suits my use. I recommend it.
I teach the Cadent, it appears in the first book as well, but ask I mentioned before I like the format of this book better.
I added the Cubine after I got Joy of Zentagle. It looks nice especially when value (shading) is added appropriately.
I also teach Twilight Zone, another addition I made since I bought Joy of Zentangle.
This is a new version of an older tangle that I taught, Ennies, I had updated my method to create the border effect, mainly because it looks cool when value is added.