finally have enough to zeta but then can't decide on who to zeta...

I'm in the same boat....honestly I'm just going to wait a bit and keep collecting zetas. When I fall out of the Top 20 I'll revisit, but I'd like to see a few more abilities roll out before I make a decision.

In the meantime, there are plenty of online videos showing off zeta abilities so you can decide which ones you like the best.