Long time player here, have Frost Queen's Crystal Jam maxed, with Black Pearl and Sea Fairy's Jam at lvl 20 and Moonlight at lvl 10.

At first I was going to put all my future investment into Moonlight, yeah she's terrible right now; but because she's terrible I assumed that meant that in the future she would get buffs and I was willing to risk it.

But then I thought about it... the best one to invest in is definitely Black Pearl, I would say even go for her instead of Frost Queen if you don't already have Frost Queen maxed.

After lvl 20 the cost of an upgrade becomes a bit much and you have to really focus on just one to get them to lvl 30. But the real reason Black Pearl is so much better than the other two is because Black Pearl is future proof.

We've seen how devastating the Beast Cookies are, and the devs knew they would be terrors so they only allow 1 per team. Mystic Flour is such a good healer, she completely put all others out of a job. they even made her weaker with safeguard cookies because them together at full power would just be unkilable.

Now imagine that level of meta breaking , for when they actually do release an attacking Beast. Black Pearl's 25% universal Dmg resist bypass is good now, but it's going to be a HUGE when they release a beast that can utilize it.