By utilizing the main Guild Wars game you are going to be limited to only a few of the character classes. Here is a list of what you will be able to choose from:
- Warrior

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- Monk
- Ranger
- Necromancer
- Mesmer
- Elementalist
If this character is only going to be used for farming dye then you are going to want a class that has strength or high damage skills. The Elementalist or Warrior is a popular class for people to choose for a pre-searing dye run. If you are going to keep your character then go ahead and choose any class type you like, all of them will work fine for this run.
Even though you can group with one other person in pre-searing it is not wise to do so for this run. You want all the dye that drops and having an additional person in your party is going to make the drops be split. This means someone else could get your dye drops insted of you. So farm solo, your friends will understand.