It is different for each line, but for lines with insufficient cooldown, the wall option is good, and for lines with a generous cooldown, the damage increase option is good. For example, in the case of the Empire Sword, the damage increase option is better than the wall option because the sword has 2x its own cooldown acceleration. It's good, and like AD, it's quick to cast but lacks cooldown, so the wall option is good and feels like this. I think it's good to think of it as making up for what's lacking. :)
Thanks for the info. Currently I am also using damage increase because ifeel ES is not lacking on cooldown..i always wait your content about ES so OP more contents to come