I have search and found many recommend book that I have listed below.
I want to know which book is your favorite ? and why you love it?
Extreme Programming Explained by Kent Beck. I grew up with that one ;-)
I can't tell you which of the above is the best book, but as I have read Agile Principles, Patterns, and Practices in C# (Robert C. Martin Series) I'll comment on that.
The book covers a lot of important points and it is good read. Unfortunately the editing leaves a lot to be desired. I got the feeling that this was really a Java book quickly translated into C#. Although a lot of the advice applies equally well to Java and C# then leftovers annoyed me.
Finally I would like to recommend another book by Robert C Martin. It is called Clean Code, and it has a lot of the same information as the aforementioned book, but it is much better edited and the advice is more immediately applicable IMO but of course YMMV.
I've read and really like Extreme Programming Explained, too, because it was such an eye opener. But for a beginner, I'd suggect "Test-Driven Development - By Example" from the same author. The reason is that agile can seem a bit overwhelming for someone who is new to software development and testing is something that you can (and should) use all the time, even in non-agile projects.
Here is a good and new book:
Clean Code: A Handbook of Agile Software Craftsmanship (Aug 11, 2008)
P.S. find more .NET related books at www.riaguy.com/books/
For me, "Agile Software Development", by Alistaire Cockburn. Here's a StackOverflow post I wrote about why I love it so much.
Several books I like very much:
It really depends upon what you want to learn about.
If you want to learn about the human side of agile then you should definately read "Agile Software Development", by Alistaire Cockburn. The discussion on failure modes of humans is fantastic.
If you want to learn about how to plan a project then Agile Estimating and Planning by Mike Cohen is the one to read.
If you want to understand how to deliver lean project and the thinking behind a lot of the lean practices which are bandied about then read "Implementing Lean Software Development: From Concept to Cash" by by Mary & Tom Poppendieck.
If you are more interested in the practical side of TDD/Refactoring/Code Design then I'd pick up one of Agile Principles, Patterns, and Practices in C# (Robert C. Martin Series).
I am currently most of the way through "Art of Agile Development" by Shore & Warden. It provides a good introduction to XP and other agile methodologies such as Scrum. Most usefully for me it explains why trying to mix and match your own set of agile principals is a bad idea until you become an expert as the subtle way the princiapals and practices support each other is not obvious until you have lived them for a while.
I'd also very highly support Charlie in his love of Alistair Cockburns Agile Software Development, a very useful book to get to understand why agile works in terms of how and why people work.
Of the list provided, my favorite is "Scaling Software Agility: Best Practices for Large Enterprises". It provides the widest coverage of Agile topics and applies the coverage against the stereotypical enterprise. The book is realistic and pragmatic. It does a good job providing evidence of the value of Agile in the enterprise and helps with selling agile to executive management and managing real life agile challenges in the enterprise. I use this book frequently as a leader of a a number agile teams.
My comments on the other books that I am familiar with:
I have not read the other two books but they do look intriguing.
The Art of Agile Development has been a great help getting my team into Agile development. Before that book I read Agile and Iterative Development: A Manager's Guide which gave me enough information about each method that I knew my team would work best using many XP practices (thus why I chose to read further into the art of agile). Although even with both of those books I'm not there yet. They will give you the basics but practical application comes from personal discovery and talking with real people applying them.
The book Agile Testing: A Practical Guide for Testers and Agile Teams is a great resource for all of the Agile team. Its an interesting perspective on how to approach delivering the goods by incorporating test into the whole process.
I am a great believer that to know a subject is to have an opinion on the subject. To have a better understanding of Agile, you have got to know your stuff outside of your comfort zone, be it design, test, development or management.
The other thing I reccomend is to be an explorer when approaching any topic in your drive to do things better, quicker, faster ... oh and don't forget right! I like to listen in and sometimes flame on people like James Bach, Elisabeth Hendrickson, James Whitaker, Misko Hervey, the one and only Joel, and the Evil Tester. Just to name a few. All of these people have helped to frame the right questions I need to ask and have helped interpret some of the ideas that agile plant in my head. Don't forget its all about the asking :)
Anyways, happy hunting!
I've voted for "Extreme Programming Explained" above but you really can't learn agile from a book any more than you can learn to ice skate by reading a book about ice skating. There's a certain amout of experimentation and practice involved in learning it.
A book on agile can only give you an impression of what agile is like. Agile isn't an exact science like physics.