A lot of mentions here I didn't read, but I suspect I would like them, too.
So, my picks:
1. Player's Handbook II
It offered a lot of good options that the splat books should have given but did not.
The Affiliations are a cool concept (even if they represent a "mild power-creep"), and they might point us to an actual alternative to Prestige Classes.
2. Eberron Campaign Setting
I love the setting. I just need a cool adventure path (à la Shackled City or Savage Tides) that I can point one of my fellow players to, so they DM the setting.
3. Unknown
After that, it becomes very difficult. Most of the other books I own are splat books, and it's difficult to identify a clear favourite. Still, from the things I used:
- Masters of the Wild: I loved the Shifter. I don't care if it was overpowered, but I just loved turning into the various monsters. Balance Wise, I prefer the PHB II Shapeshifting rules, though I admit I wonder if a Shifter with these rules would have been the same fun. My favorite forms where Elephant and Delver, even though I usually used others for
Power gaming.. "tactical reasons". Maybe I just need to adapt the Bear Warrior class to Elephant Warrior class? Oh, and it had the Oozemaster, which was just to funny to miss (never played or had one in my game, but the idea alone was just to great
).
- Complete Arcane: The Warlock. I really like him.
- Complete Divine: Radiant Servant of Pelor is great, even though I normally hate playing Clerics.
