>>36440290It matters what you are trying to beat and other mons you expect to face. Unless the base speed is massive, most things opt to go Jolly/Timid or Hasty/Naive to outspeed their opponent.
Certain things have little chance to move first so they can just go for damage (Adamant/Modest)
There is also Trick Room in which you'd want the lowest speed in order to move first (Brave/Quiet)