Originally Posted by antonn

Is either the "Enemy ATK down" or "Skill activation Rate" significantly better than the other if you only have 1 in a group? Trying to decide between 2 girls with the 5* ticket, and can't make up my mind.

If you have only either one of those within a squad, then I'd say the Enemy ATK down skill adds more to the survivability of your squad (which means your units survive longer and thus deal more damage in the long term) than the Skill Activation Rate would add to its DPS.

On the other hand, if you plan to make dedicated squads in the long run, then a Skill Activation Rate squad is much easier to form than an ATK down squad, it's more probable you'll gather random additions to such a squad from gachas and events, simply because there are more of them, especially when you also take bloomed forms into consideration.

Looking at an even longer term, assuming you eventually gather both a dedicated ATK-down squad and a dedicated Skill Activation Rate squad, it's very interesting how the two have different strengths. ATK-down squads are great against raidbosses, while Skill Activation Rate Squads are much better at wiping out the smaller trash-mob pests and map-bosses.
Simply put:
My ATk-Down squad tends to deal 2-3 times more damage against raidbosses than my Skill Activation squad. But my Skill Activation squad (by now) wipes out the pests on the whale maps on the first round of combat, without taking a single hit, while my ATK-down squad does take damage from those.