Personally, I think autobiographies are best written after a player's career is over and they have had a chance to look back and reflect. Also they can be honest without having to think of their image/sponsors etc.
I don't read many autobiographies but I really enjoyed John McEnroe's and came away with the impression he was being honest about himself. It was also well written. Nadal's, and I speak as a fan, was pretty bland but still worth a flick through.
At the risk of repeating myself the two biographies (auto or not) I would like to read are Lendl's and Edberg's.
General tennis books
Courts of Babylon - good but I remember it had some factual mistakes that even I managed to spot. Also the author came across as a bit self-righteous.
Hard Courts by John Feinstein (?) - Brilliant; insightful and well written
Strokes of Genius, Jon Wertheim's book about the 2008 Wimbledon final, I liked a lot too.