Since Cady doesn't seem to be around very often and many things changed since his 3.1 BHGA list, I decided to shamelessly steal his idea and put the updated list here (you can replace Constellus with Furious Gladiator Mageblade to get even a bit better results). For those who want the details, here is the spreadsheet (for both Draenei and non-Draenei).
If you spot any error in the math below, feel free to correct me.

3.1.2 Contending Hit Items:


Head: [Conqueror's Circlet of Sanctification] vs [Collar of the Wyrmhunter]
- Gain 51 hit, Lose 76.27 pp
- Hit/DmgLost = 51/76.27 = 0.67

Neck: [Pendant of the Shallow Grave] vs [Pendant of Fiery Havoc]
- Gain 46 hit, Lose 19.25 pp
- Hit/DmgLost = 46/19.25 = 2.39

Cloak: [Pennant Cloak] vs [Drape of Mortal Downfall]
- Gain 41 hit, Lose 8.18 pp
- Hit/DmgLost = 41/8.18 = 5.01

Chest: [Conqueror's Raiments of Sanctification]
- Gain 74 hit, Highest pp in slot with set bonus
- Obvious choice

Wrist: [Grasps of Reason] vs [Bracers of Unleashed Magic]
- Gain 36 hit, Lose 30.23 pp
- Hit/DmgLost = 36/30.23 = 1.19

Gloves: [Pharos Gloves] vs [Pulsar Gloves]
- Gain 56 hit, Lose 60.89 pp
- Hit/DmgLost = 56/44.75 = 0.92

Waist: [Starwatcher's Binding] vs [Sash of Ancient Power]
- Gain 43 hit, Lose 27.01 pp
- Hit/DmgLost = 43/27.01 = 1.59

Legs: [Leggings of the Enslaved Idol]
- Gain 70 hit, Highest pp in slot
- Obvious choice

Feet: [Treads of the False Oracle] vs [Sandals of Rash Temperament]
- Gain 57 hit, Lose 66.99 pp
- Hit/DmgLost = 57/66.99 = 0.85

Ring: [Conductive Seal] vs [Shimmering Seal]
- Gain 42 hit, Lose 36.58 pp
- Hit/DmgLost = 42/36.58 = 1.15

Trinket: [Illustration of the Dragon Soul] vs [Dying Curse]
- Gain 71 hit, Lose 47 pp
- Hit/DmgLost = 71/47 = 1.51

Weapon: [Constellus] vs [Starshard Edge]
- Gain 39 hit, Lose 11.54 pp
- Hit/DmgLost = 39/11.54 = 3.38

Off-hand: [Cosmos]
- Gain 51 hit, Highest pp in slot
- Obvious choice

Wand: [Scepter of Lost Souls] vs [Petrified Ivy Sprig]
- Gain 29 hit, Lose 8.48 pp
- Hit/DmgLost = 29/8.48 = 3.42



Best to Worst Hit Items:

1. [Conqueror's Raiments of Sanctification], 74 hit, 0 pp lost
2. [Leggings of the Enslaved Idol], 70 hit, 0 pp lost
3. [Cosmos], 51 hit, 0 pp lost
4. [Drape of Mortal Downfall], 41 hit, 5.01
5. [Petrified Ivy Sprig], 29 hit, 3.42
6. [Starshard Edge], 39 hit, 3.38
7. [Pendant of Fiery Havoc], 46 hit, 2.39
8. [Sash of Ancient Power], 43 hit, 1.59
9. [Dying Curse], 71 hit, 1.51
10. [Bracers of Unleashed Magic], 36 hit, 1.19
11. [Shimmering Seal], 42 hit, 1.15
12. [Pulsar Gloves], 56 hit, 0.92
13. [Sandals of Rash Temperament], 57 hit, 0.85
14. [Collar of the Wyrmhunter], 51 hit, 0.67



Highest Pseudopower Combination:

[Conqueror's Raiments of Sanctification], 74 hit, 0 pp lost
[Leggings of the Enslaved Idol], 70 hit, 0 pp lost
[Cosmos], 51 hit, 0 pp lost
[Drape of Mortal Downfall], 41 hit, 5.01
[Petrified Ivy Sprig], 29 hit, 3.42
[Conqueror's Handwraps of Sanctification] with Veiled Monarch Topaz, 12 hit, 1.2
Hit Total: 277 + 12 (Icewalker) = 289



3.1.2 Endgame List (updated June 15th, '09)

Helm: [Conqueror's Circlet of Sanctification] - Thorim (Ulduar 25)

Neck: [Pendant of the Shallow Grave] - Thorim (Ulduar 10, Hard)

Shoulders: [Conqueror's Mantle of Sanctification] - Yogg-Saron (Ulduar 25)

Cloak: [Drape of Mortal Downfall] - Iron Council (Ulduar 25 Hard)

Chest: [Conqueror's Raiments of Sanctification] - Hodir (Ulduar 25)

Bracers: [Grasps of Reason] - XT-002 (Ulduar 25, Hard)

Gloves: [Conqueror's Handwraps of Sanctification] - Mimiron (Ulduar 25)

Waist: [Starwatcher's Binding] - Algalon (Ulduar 25)

Legs: [Leggings of the Enslaved Idol] - Freya (Ulduar 25, Hard)

Feet: [Treads of the False Oracle] - Yogg-Saron (Ulduar 25, Hard)

Ring 1: [Nebula Band] - Algalon (Ulduar 10)

Ring 2: [Conductive Seal] - Mimiron (Ulduar 25, Hard)

Trinket 1: [Flare of the Heavens] - General Vezax (Ulduar 25, Hard)

Trinket 2: [Illustration of the Dragon Soul] - Sartharion (Obsidian Sanctum 25)

Mainhand: [Constellus] - Hodir (Ulduar 25, Hard) and Algalon (Ulduar 25)

Off-Hand: [Cosmos] - Algalon (Ulduar 25)

Wand: [Petrified Ivy Sprig] - Freya (Ulduar 10, Hard)

The way I figured out which hit items to take is to make a table containing each contending hit item, and choosing pieces that gave you the most amount of hit for the least amount of sacrificed pseudo damage. Tell me if this makes sense, I've never been stellar at math but here's what I came up with.

Contending Hit Items:

Neck: [Wyrmrest Necklace of Power] vs [Cosmic Lights]
- Gain 33 hit, Lose 1.72 PP (pseudopower)
- Hit/DmgLost = 33/1.72 = 19.19

Shoulders: [Valorous Mantle of Faith] vs [Mantle of Dissemination]
- Gain 41 hit, Lose 21.34 PP
- Hit/DmgLost = 41/21.34 = 1.92

Chest: [Gown of the Spell-Weaver] vs [The Sanctums Flowing Vestements]
- Gain 72 hit, Lose 26.35 PP
- Hit/DmgLost = 72/26.35 = 2.73

Chest: [Heigan's Putrid Vestemends] vs [The Sanctums Flowing Vestements]
- Gain 49 hit, Lose 19.23 PP
- Hit/DmgLost = 49/19.23 = 2.55

Wrist: [Bindings of the Expansive Mind] vs [Unsullied Cuffs]
- Gain 28 hit, Lose 23.48 PP
- Hit/DmgLost = 28/23.48 = 1.19

Gloves: [Gloves of Grandeur] vs [Valorous Handwraps of Faith]
- Gain 38 hit, Lose 39.01 PP
- Hit/DmgLost = 38/39.01 = 0.97

Waist: [Cincture of Polarity] vs [Leash of Heedless Magic]
- Gain 43 hit, Lose 30.8 PP
- Hit/DmgLost = 43/30.8 = 1.4

Legs: [Leggings of the Wanton Spellcaster] vs [Leggings of Mortal Arrogance]
- Gain 82 hit, Lose 32.89 PP
- Hit/DmgLost = 82/32.89 = 2.49

Feet: [Boots of Impetuous Ideals] vs [Arcanic Tramplers]
- Gain 37 hit, Lose 18.2 PP
- Hit/DmgLost = 37/18.2 = 2.03

Offhand: [Surplus Limb] vs [Accursed Spine]
- Gain 32 hit, Lose 10.56 PP
- Hit/DmgLost = 32/10.56 = 3.03

Wand: [Gemmed Wand of the Nerubians] vs [Plague Igniter]
- Gain 18 hit, Lose 6.33 PP
- Hit/DmgLost = 18/6.33 = 2.84

Trinket: [Dying Curse] vs [Sundial of the Exiled]
- Gain 71 hit, Lose 12.35 PP
- Hit/DmgLost = 71/12.35 = 5.75



That means the top hit items from best to worst are as follows:

1. [Wyrmrest Necklace of Power] (19.19), 33 hit
2. [Dying Curse] (5.75), 71 hit
3. [Surplus Limb] (3.03), 32 hit
4. [Gemmed Wand of the Nerubians] (2.84), 18 hit
5. [Gown of the Spell-Weaver] (2.73), 72 hit
6. [Heigan's Putrid Vestemends] (2.55), 49 hit
7. [Leggings of the Wanton Spellcaster] (2.49), 82 hit
8. [Boots of Impetuous Ideals] (2.03), 37 hit
9. [Valorous Mantle of Faith] (1.92), 41 hit
10. [Cincture of Polarity] (1.4), 43 hit
11. [Bindings of the Expansive Mind] (1.19), 28 hit
12. [Gloves of Grandeur] (0.97), 38 hit


Using those numbers we can find the most efficient hit pieces to reach a hit rating of 277 (289 with the icewalker enchant) with.

The highest psuedopower combination I've come up with so far is:

[Wyrmrest Necklace of Power] (19.19), 33 hit
[Dying Curse] (5.75), 71 hit
[Gemmed Wand of the Nerubians] (2.84), 18 hit
[Gown of the Spell-Weaver] (2.73), 72 hit
[Leggings of the Wanton Spellcaster] (2.49), 82 hit

Hit Total: 276 + 12 (Icewalker) = 288

Tell me what you all think ^_^

-edited with better math stuffis-

My question now: 0,05% hit missing? do i notice this in dps?

http://chardev.org/?template=125829

I like this one, you can switch wand for more hit.

EDIT:
Why are people putting the other purple gem in the belt and not in both the neck and back which both have a 5sp socket bonus for blue?