Crunch covers Ghost and Psychic, whereas Brick Break covers Rock, Steel, Ice, Normal, and Dark.
So that way, Brick Break is better. Besides, it also breaks Light Screen/ Reflect, so that's a bonus too. I'd say go with Brick Break, although it has (only) 5 less Base Power.
P.S: Switch Aqua Tail with Waterfall: Better accuracy + Flinch rate.