Aldor vs Scryer
The Aldor and Scryer are two factions that reside within Shattrah city in Outlands. At a certain level, you can choose between the two. Gaining reputation for one would reduce the other by 10% more of the amount of reputation gained. The process can be reversed though but it takes a bit of grinding to get back to exalted. The Aldor is composed of draenei while the Scryers is composed of blood elves. This has some slight implications if your character is either of the two races. Draenei start off as friendly with the Aldor and unfriendly with the Scryers; the opposite is true for blood elves.
Each faction has their own camp within Shattrah city with separate elevators that lead to each one. The Aldor’s rise is much higher compared to that of the Scryer’s tier. It might not be so important but impatient players may benefit from choosing the Scryers. Jumping from Aldor’s rise will surely lead to death but it’s survivable from the Scryers tier.
If you are a jewelcrafter, it may be more sensible to go with Aldor, or at least defer siding with the Scryers. The jewelcrafting trainer is located in the Aldor rise, and although siding with the Scryers would not disqualify you from learning from him, the guards there would be hostile towards you and would probably attack you when you come into range.
Almost all of the differences cited above would probably become negligible once you go above the prime levels for Outlands. The only thing that you would probably find important is the bonuses provided by the shoulder inscriptions that both factions provide. The inscriptions provided by the Aldor tend to provide damage, attack power, healing, and dodge. With the Scryers, the inscriptions provide crit, defense, and mana regeneration. That should provide you with a guide on whether to choose the Scryers or Aldor based on the stats that you would be needing for your build.
Summary:
1. The Aldor is composed of draenei while the Scryers is composed of blood elves
2. The Aldor rise is much higher from the ground compared to the Scryer’s tier
3. The jewelcrafting trainer in Shattrah is located in the Aldor rise and not in the Scryer’s tier
4. Aldor shoulder inscriptions tend to provide damage, attack power, healing, and dodge while Scryer’s shoulder inscription tend to provide defense, crit, and mana regeneration