Sentimental memories come to mind with several, and anything by Roger Angell would be a candidate. The first book I must mention which changed how I viewed the game was "The Hidden Game of Baseball", and I intend to read it again someday, but I have discovered that I'll have to buy a reprint, because the original is now moldy.
In the meantime, one book I look forward to rereading is Bill James' Baseball Historical Abstract. This one is not moldy, and I'm now taking precautions over protecting the boxes and shelves from moisture.
Technically, the most impressive book I've read is Willie Mays' biography: "The Life, The Legend", by James Hirsch. A very, very well-researched book which was still entertaining and which did not uncover dirt, but celebrated Willie.
Catfish Hunter, RIP. Mark Fidrych, RIP. Skip Caray, RIP. Tony Gwynn, #19, RIP
A fanatic is someone who can't change his mind and won't change the subject. -- Winston Churchill.
Experience is the hardest teacher. She gives the test first and the lesson later. -- Dan Quisenberry.