Depends on what you're looking for.
As far as what's been mentioned,
Brewing Classic Styles is a good source for proven recipes and some style knowledge.
Designing Great Beers is great for learning to design your own.
How To Brew is good for general brewing technique.
Brewing Better Beer assumes you know what you're doing already but will help you elevate to the next level, from good to award winning.
For me, I've gravitated beyond general brewing texts, and am generally not interested in broad, dedicated recipe books unless they have something else to offer (like style history). I've been reading more specific brewing science, and more foundational, technical books. The "Brewer's Element" series (ie Malt, Hops, Yeast, and Water) is good. Style-specific books are good as well (just read Sutula's Mild Ale, Brew Like a Monk, American Sours, Wild Brews, IPA, etc). Read a book dedicated to cellarmanship/cask maintenance (Cellarmanship is the not so ironic title). Just started a book specifically on QC/QA/consistency (Bamforth's Standards of Brewing). And brewing science texts are good too.