Torpedo or Cannon?

If it's +15% per hit, then it's really pomegranatety compared to +20 WATK, since +15% per hit is 1.05x increase in damage for Cannon, and 1.016x increase for Torpedo, whereas you would need 400 WATK for +20 WATK to be that pomegranatety of an improvement.

I'm almost certain counter attack is +15% of your damage in that hit (a sh'itton of difference, from personal experience), similar to +30% damage to bosses or whatever boost adv homing gives. 30k x5 would turn into 34.5k x5, and with apples your damage increase would be a LOT more, helping bossing significantly.