Mustrum_Ridcully
Hero
Flavor text heavy books that are inspirational and can be pillaged for campaign elements. Monster books with more flavor text and ecology (and a knowledge check chart with one line per range of numbers is not a good ecology section, it's a cheap way out of writing one). Setting books and supplements with lots of world elements, history, etc.
Anything but more classes, feats, powers, PrCs, etc etc
I like the knowledge check parts mostly because they are directly usable in game. If I want to know what the PCs should know and what not I just consult the chart and let them roll. At the same time, they don't "over define" a monster for me.
For now, I am planning to use the H1 to E3 series of adventure books, but eventually I _will_ homebrew, and more monster fluff is no longer inspirational to me, but limiting. I feel like I am throwing away way too much information.