Being good at the game is not always sufficient. At some point it’s not enough anymore. One could have a higher rating or better dps simply from optimal professions. Unfortunately, gathering professions don’t offer such optimization. So yeah, spoiler alert, it will be necessary to have another character or a lot of gold to grind two crafting professions on a single character.
We will only cover the Binds when Picked up (BoP) items here and why one profession is better than another. Then, depending on what your goals are, you have multiple options.

PvE Rogue: The optimized profession for raiding and heroics

Enchanting

The only purpose of the enchanting profession is to add +4 all stats on your rings.
Once both best in slot rings are enchanted, you should consider dropping it for another profession.

Leatherworking

On The Burning Crusade, Leatherworking offers a lot of useful items both for yourself and your group such as Drums:

Having those is a prerequisite to apply in certain guilds, but Blizzard revealed that drums might not need Leatherworking to be used, which is a big news.
The T6.5 chest Carapace of Sun and Shadow is best in slot and it’s a bind when picked up. That’s why Leatherworking is a great choice for a rogue wishing to be optimal for PvE content.
It also offers nice shoulders to start farming heroics and raids (Switfstrike Shoulders) if you do not have a decent gear part yet (like the Wastewalker Shoulderpads from D3 Wastewalker Set for example)

Jewelcrafting

This profession will give you unique superior gems (+12 hit rating, yellow gem); a best in slot neck for both PvP and PvE (Hard Khorium Choker – T6.5, which is part of our Endgame Rogue BiS List as well), a great starter trinket for both PvP and PvE (Figurine – Shadowsong Panther) and a lot of gold 😉. Every player needs gems, don’t forget that.

In case you are wondering, there is below a comparison between +24 Attack Power unique gem and +10 agility gem.
Please, don’t craft the +24 Attack Power gem!

Engineering

This an interesting profession with good Binds when picked up gear but not best in slot, at least in PvE.
Honorable mention to Quad Deathblow X44 and X11 Goggles. They’re great, but not the best. There is also a great interest for Battle Chicken because they can buff the whole raid with their ability Battle Squawk (5% haste).

PvP Rogue: The optimized professions for Battlegrounds and arenas

Enchanting

The only purpose of this profession is to add +4 all stats on your rings.
Once both best in slots rings are enchanted, consider dropping it for another profession.

Jewelcrafting

In a PvE mindset? It is worth taking care of the gem optimization and leveraging the unique +12 hit rating gem. In PvP, you will mainly use agility gems. This unique aspect of Jewelcrafting is also good because you can create a +12 Agility unique gem. In a sense, the +24 Attack Power(Crimson Sun) gem is way worse than a +10 agility, so we do not recommend to craft it.

Let’s compare with Agility Equivalence Points:

          • 1 Agility gives 2.47 Attack Power, 0.025 Crit Rating and Dodge
              • +10 agility offers 24.7 Attack Power
              • +10 agility also offers 0.25 % Crit Chance
              • 0.25% Crit Chance = (22*0.25) 5.5 Crit Rating.
              • 5.5 Crit Rating indirectly offers (5.5 * 0.88 *2.17) 10.5 Attack Power.

Meaning that +10 agility gives roughly 35.2 Attack Power and dodge %. This is far better than the +24 Attack Power unique gem.

In PvP, depending on your gear and your team composition, you will build up agility and/or attack power. Jewelcrafting offers unique gems with improved agility or attack power. When it comes to details to win a game, this would count.

What is important and the reason why we advise any rogue to pick Jewelcrafting is the trinket! Figurine – Shadowsong Panther increases effective stealth by 1. It may not look like a lot but it makes a huge difference when you combine it with the human racial (Perception). and the engineering head which we will cover shortly… Sbkzor wrote a very informative in-depth stealth guide, make sure to read it if you search for more information on this topic.

Noteworthy is also the endgame T6.5 necklace Hard Khorium Choker. Best in slot in PvE, and a really good item for PvP as well.

For these reasons, Jewelcrafting makes a great candidate for a PvP and PvE rogue profession…

Engineering

Oooooh boy, here comes the fun! Engineering is both efficient and extremely fun for PvP. It’s competitive, requires skill, and is very rewarding; particularly when you anticipate where a mage is going to blink at and you throw a grenade at the exact spot!
Anyway, as a rogue, being stealthy is important (duh!) and we saw earlier that Jewelcrafting provides more effective stealth. In a similar vein, Engineering helps you increase stealth detection with Quad Deathblow X44 and X11 Goggles.

With the combination of effective stealth and stealth detection, the rogue dramatically increases the chances he has to have the upper hand during a fight against stealthy characters such as other rogues and druids. It may not look that impressive but those are the most played classes in PvP.
It cannot be stressed enough how important it is for a rogue to have the opener. It’s a game-changer, an enormous pressure on the opponents.
Let’s talk about the other tools that can be handy as a rogue with Engineering:

          • Frost Grenade (335): Root every enemy in the blast range for 5sec. A pretty great tool against warriors for additional controls.
          • Fel Iron Bomb (300): Stun every enemy in the blast range for 3sec.
          • Arcane Bomb (300): Silence every enemy in the blast area for 5sec + drain 50% mana of the damage done.
          • Dark Iron Bomb (285): Stun every enemy in the blast range for 4sec.
          • Parachute cloak (225): Reduces the fall speed for 10sec. Combined with the next gadget and you have a fun way to fly in Alterac or across Warsong!
          • Rocket Boots Xtreme: +300% speed for 3sec. When faded, deals a bit of damage that can be used to break a cc like a polymorph, blind, gouge, or anything else that breaks on damage. To be used for fun or to break an anticipated cc. [warning: cannot be used in arenas in 2.4.3]
          • Gnomish Cloaking Device: Invisibility for 10sec (not stealth, IN-VI-SI-BI-LI-TY!). A great and dramatic escape … with 1h CD.
          • Goblin Land Mine: To be placed around a flag or a capture point to spot stealth enemies.
                    • Gnomish Engineering:
              • Gnomish Poultryizer (340): Turns the target into a chicken for 15sec. This is my favorite toy in the game. A silence of FIFTEEN SECONDS! FIFTEEN!
              • Nigh Invulnerability belt (350): Absorbs 4000 damages for 8sec. This fails around 15% of the time and… doubles the damage taken from all sources. Extremely popular in arenas during Season 1
              • Gnomish Flame Turret (325): Quickly constructs a gnomish flame turret at your feet that will nearly always attack nearby enemies. It’s so fun to use that to mess with enemies trying to cap a flag. It does cost a lot given its inefficiency but IT’S FUN.
              • Gnomish Alarm-O-Bot (265): Summons an Alarm-O-Bot for 2 minutes that occasionally sends out a pulse that detects nearby stealthy or invisible enemies. This one is also so fun in battlegrounds. How often do you see one of those there? Not very often, I guess. ORIGINAL CONTENT! Make them laugh and then kill them mercilessly.
                    • Goblin Engineering:
              • The Big One (235): Inflicts 340 to 460 Fire damage and incapacitates targets for 5 seconds in a 10-yard radius. TEN YARD RADIUS, FIVE SECONDS STUN. You couldn’t miss your target even if you were blind. 
              • Super Sapper Charge (340): Explodes when triggered dealing 900 to 1500 Fire damage to all enemies nearby and 675 to 1125 damage to you. This is an absolute must-have to duel rogues and break their vanish.
              • Goblin Sapper Charge (205): Super Sapper Charge’s little brother. Less damage but same purpose. Costs less to make..
              • Goblin Rocket Boots (225): A sprint of 20sec with 30% chance of failure. Meh. 5 Min CD Cool! If they malfunction, they’re destroyed… Just go for the gnome version. Basically, Goblin boots are faster with shorter cooldown, Gnomish boots are safer with longer cooldown.

You know pretty much everything about the optimized professions for Classic The Burning Crusade from a rogue perspective. So, now, you can select your favorite one and start leveling your character!

TL;DR: What is the best TBC Rogue Profession?

PVE

      • Engineering (Battle Chicken, Goggles)
      • The second profession is up to you but we would start with enchanting, until endgame BiS rings, then pick Jewelcrafting.

Blizzard announced that Drums would not require Leatherworking to be used, which means that rogues do not need to take this profession

PVP

      • Engineering (Goggles if available at launch, Invulnerability belt during S1 especially as double DPS)
      • Jewelcrafting (Unique gems, Shadowsong Panther)