With The Burning Crusade comes a whole set of new enchants that you are going to use.
Without surprise, most of them come from enchanting, except head & shoulder (from reputation) and legs (leatherworking).
We used AEP comparison to determine what are the best enchants! 

BIS Enchants

This is a list of the best enchantments throughout the extension for most slots, but for a few of them, a discussion can be made, especially for PVP.

Head: Glyph of Ferocity
Shoulder: Greater Inscription of Vengeance*
Cloak: Greater Agility (PVE, PVP) / Stealth (PVP)
Chest: Exceptionnal Stats
Wrist: Assault
Gloves: Superior Agility
Legs: Nethercobra leg Armor
Boots: Cat’s SwiftnessDexteritySurefooted*
Rings: Stats
Weapons:  Mongoose*

AEP Enchant Comparison for each slots

Let’s make an AEP comparison of each enchant to explain how we decided which enchant is the best.
In this guide, we use the T4 combat weight of stats for the comparison (note that you will end up with the same best enchant with almost every spec or phase regardless).

Combat sword Strength Agility Critical Hit Exp Haste
T4 stat weight 1,1 2,26 1,83 2,54 2,77 2,2

If you need help to understand how the weights of stats and the AEP values system works, make sure to read this guide.

The best TBCC rogue Head enchant

Head
Enchant Source Effect AEP Value
Glyph of ferocity Revered Cenarion Exp 34 AP / 16 Hit rating 75
Death’s Embrace Zul’Gurub Enchant 28 AP / 12 dodge rating 28
Glyph of the Gladiator Revered Shattered Sun 18 stam / 20 resilience /

For the head slot, Glyph of ferocity is a clear winner from a damage standpoint.
Glyph of the Gladiator comes out in phase 5 and might be a choice to balance out a very offensive PVP setup with 4 pieces T6 alongside 4 piece Arena set (thanks to T6 wrist/waist/boots pieces coming from Sunwell).

The best TBCC Rogue shoulders enchant

Shoulder
Enchant Source Effect AEP Value
Might of the Scourge Drop in Naxxramas 26 AP / 14 Crit rating 52
Greater Inscription of Vengeance Exalted with Aldor 30 AP / 10 Crit rating 48
Greater Inscription of the Blade Exalted with Scryers 20 AP / 15 Crit rating 47
Zandalar’s Might Exalted with Zandalar 30 AP 30

If you want to be really sweaty, the actual best enchant for PVE is dropping on Saphiron in Naxxramas!
For PVP Aldor remain the best choice as it provides you with more AP compare to the two other with more crit rating.

Note: while gearing up you might use honored Aldor or Scryers enchant which are not listed here (and worse than even ZG enchant). 

Make sure to read this article

The best TBCC rogue cloak enchant

Cloack
Enchant Source Effect AEP Value
Greater Agility Enchanting (trainer) 12 agility 27
Stealth Enchanting (AQ40 drop or Cenarion Exp Exalted) +5 stealth score /

For PVE there is no choice: +12 agility is a must-have.
For PVP, stealth could become the go-to enchant as openers matter a lot in the arena. The Panther from jewel crafting alongside Greater Agility is also a great alternative to Bloodlust brooch and stealth enchant (see jewel crafting guide). Ultimately you could also opt for stacking both but we slip into another topic covered in our stealth and detection guide.

Note that there is also magic resistance enchant on the cloak which will be used for specific raiding encounters (like the +20 shadow resist for Mother Shahraz in BT).

Check our ultimate in-depth Stealth Guide

The best TBCC rogue chest enchant

Chest
Enchant Source Effect AEP Value
Exceptional Stats Enchanting (Honor Hold/Thrallmar  Revered) +6 all stats 20
Major resilience Enchanting (World Drop) 15 resilience /

Exceptional stats is the right pick, but you might want to use the resilience enchant for arenas to balance out an offensive build (with a lot of PvE gear parts) and this is way better than the head enchant since you have way more resilience compared to the AEP lose.

Note that there is also a magic resistance armor kit from leatherworking that can be put on the chest, gloves, legs, and feet for specific raid encounters.

The best TBCC rogue wrist enchant

Wrist
Enchant Source Effect AEP Value
Assault Enchanting (Trainer) 24 AP 24

Only one option, but what a great one!

The best TBCC rogue gloves enchant

Gloves
Enchant Source Effect AEP Value
Superior Agility Enchanting (AQ40 Drop or Keepers of Time Exalted) 15 agility 34
Assault Enchanting (trainer) 24 AP 26
Minor Haste Enchanting (trainer) 10 haste rating 22

There is no discussion here Superior Agility is the best one.

The best TBCC rogue leg armor enchant

Legs
Enchant Source Effect AEP Value
Nethercobra leg Armor Leatherworking (Honor Hold / Thrallmar exalted) 50 AP / 12 Crit rating 72
Nethercleft Leg Armor Leatherworking (Cenarion exp exalted) 40 Stam / 12 Agility 27
Death’s Embrace Zul’Gurub Enchant 28 AP / 12 dodge rating 28

Nethercobra leg armor is the obvious winner here. His tanking counterpart might be of some use early on when you don’t have much resilience and need to be less squishy.
Note that there is a blue version of those leg armor kits that will be useful on early gear since they are a lot cheaper.

The best TBCC rogue boots enchant

Boots
Enchant Source Effect AEP Value
Dexterity Enchanting (Drop in Auchenaï Crypt) 12 Agility 27
Surefooted Enchanting (Drop in Karazhan) 10 hit rating & 5% resist to snare and root 25
Cat’s Swiftness Enchanting (World Drop) 6 agility + 8% run speed 14
Boar Speed Enchanting (World Drop) 9 stamina + 8% run speed /

Since we’ve got Relentless Earthstorm Diamond from the start (and you should go for it) there is a lot less discussion about boot enchant, and you absolutely need to have speed on it, your best one would be obviously Cat’s Swiftness but if you can’t get it, go for Boar’s Speed or even the good old Minor speed increase from Vanilla! If you have some doubt about that, check our guide dedicated to speed enchant.

The only exception I can think of is for speedrunners using Swiftness of Zanza (which is a guardian elixir and by far the best one for both survivability and DPS). In this case, you might want to use Surefooted as the AEP value is close to dexterity but the 5% resistance to snare and root might comes in handy, and even so you should have a spare pair of boots with speed to slap on in case you die.

The best TBCC rogue rings enchant

Rings (only for Enchanter)
Enchant Source Effect AEP Value
Stats Enchanting (Lower City Honored) +4 all stats 13,1
Striking  Enchanting (Consortium Revered) +2 weapon damage 12,5

Rings enchant stats comes ahead by a tiny bit for Combat Rogue, but also provides a bit of dodge and some stamina on top of pure damages which makes it also better for PVP.
On the other hand, Striking will provide a better damage output for Combat Dagger and Mutilate Specs (thanks to weapon damage modifier on Backstab and Mutilate).

Major Blizzard update announced during the Beta (April,15, 2021)

The best TBCC rogue weapon enchant

Weapon (MH/OH)
Enchant Source Effect AEP Value
Mongoose Enchanting (Moroes in Karazhan) 120 agility & 2% attack speed for 15 second 260/141
Executioner Enchanting (Zul’Aman boss drop) 840 ArP for 15 second 126/68
Crusader Enchanting (Western Plaguelands drop) 60 strengh for 15 second 121/66
Greater Agility Enchanting (Violet Eye Exalted) 20 Agility 44/44
Major Striking Enchanting (Consortium Honored) +7 weapon damage 27/17

Mongoose is your best choice from the get-go for both main hand and offhand but you might want to use Crusader in early phase 1 until you get your BIS weapons since it should be cheaper.

There’s a nice use case of Greater agility if you have a dagger MH for occasional ambushes in PVP. You may also consider it for your third and fourth off-hand (mind-numbing poison, and eventually deadly poison if you use it).

Last but not least, Executioner will outscale Mongoose on your MH later when getting a lot of Armor Penetration, and also depending on boss armor. (you can have only one Executioner buff while you can have two crusader or mongoose buffs).

That’s all for the enchant guide, make sure to check our next guide about gems.

Read more about the rogue stats & optimizations