Your Top 5/10 Favorite WotC Supplementary Rulebooks

[Shroomy]

In no particular order:

1. Magic Item Compendium
2. Spell Compendium
3. MMII
4. MMIII
5. Fiend Folio
6. Complete Adventurer
7. Complete Arcane
8. DMG II
9. Libris Mortis
10. Stormwrack

 

[Kunimatyu]

1. Spell Compendium
2. PHB 2
3. MM3
4. Complete Arcane(for Warlock)
5. Lords of Madness

 

[Asmor]

These two see the most use:

1. Magic Item Compendium
2. PHB 2

These next ones don't see an especially great amount of use, but I really like them. No particular order.

3. Complete Scoundrel
4. Complete Mage
5. Complete Arcane
6. Heroes of Horror
7. Lords of Madness
8. Fiendish Codex I
9. Fiendish Codex II
10. Tome of Battle: The Book of Nine Swords

Honorable mention:

Spell Compendium: I want to love this, I really do, but it's never come up in game because none of my players ever opt to use it and I usually try to keep NPC spellcasters simple. It's also not the sort of book you can sit there and read... so it gets honorable mention.

I should also mention that I consider the XPH to be core, or else I'd list it and probably bump heroes of horror.

 

[ShadowofDeus]

In order of increasing awesomeness:

5) Tome of Magic - I will one day prove the Shadowcaster isn't entirely useless in a prolonged setting.

4) Manual of the Planes - Think you've been there or done that? <evil laughter>
3) Sandstorm - I take so many feats from here.
2) Spell Compendium - Cured my back problems.
1) Libris Mortis - My favorite character ever... Lvl3 wiz, lvl3 cleric, level 14 true necromancer. (I started playing this character at level 1) Mind you, this was before the errata on summon undead spells. You know, the one that imposed a hit dice requirement instead of a size requirement?

Libris Mortis - 30 dollars.
Necromancer Fig - 3 dollars.
Pizza - 12 dollars.
The look on your dungeon master's face as you drop a gray render zombie on your enemy from 40 feet up - priceless.

 

[ivocaliban]

Outside of the core three:

1) Unearthed Arcana
2) Spell Compendium
3) Player's Handbook II
4) Magic Item Compendium
5) Complete Adventurer

 

[megamania]

Draconomicon
PHB
Manual of the Planes
Fiend Folio
Complete Warrior (feats)

 

[mhacdebhandia]

In no particular order:

• Tome of Battle: The Book of Nine Swords
• Lords of Madness
• Expanded Psionic Handbook
• Heroes of Horror
• Tome of Magic: Pact, Shadow, and True Name Magic
• Libris Mortis
• Complete Warrior
• Complete Arcane
• Complete Mage
• Player's Handbook II

 

[TroyXavier]

1. Draconomicon
2. Expanded Psionics Handbook
3. Complete Mage
4. Races of Stone
5. Players Handbook II
6. Libris Mortis
7. Sandstorm
8. Races of the Dragon
9. Unearthed Arcana
10. Stormwrack

Lords of Madness and Frostburn just misisng it

 

[Set]

1. PHII
2. Heroes of Horror
3. Complete Arcane
4. Complete Mage
5. Complete Warrior
6. Complete Divine
7. Libris Mortis
8. Book of Vile Darkness
9. Draconomicon
10. Unearthed Arcana

 

[Agamon]

1. Magic Item Compendium
2. PHB2
3. Spell Compendium
4. Complete Adventurer
5. Libris Mortis
6. Complete Warrior
7. Book of Vile Darkness
8. Complete Arcane
9. Unearther Arcana
10. Lords of Madness

I haven't picked up the DMG2, FCs or DotU yet. I'm sure they fit in here somewhere.