Which Legend for 1st unlock?

I would unlock in this order.

1st Octane (one of the best in the game imo)

2nd Mirage

3rd Caustic

Caustic have a big hitbox, his traps and have just received a buff as they were to weak. I think he will receieve yet another buff.

Mirage was better in the beginning, his Q isn’t really effective. People have suggested that his Q should send out random legends - that would be a nice buff. 

The ultimates of Mirage is seldom effective as most people will still spot you and you can still take damage withouth being able to counter. 

The ultimate of Caustic should be quadrupled in size and deal twice the damage - as of now it’s just working as smoke