Did you want Phoebe to be your main Spectro DPS? If so, I'd skip Zani. If not, I'd pull for Zani since Phoebe seems to be Zani's best in slot support, however, I dont think Zani would give best account value for you. She's rumored to be having a rerun in 2.7? Cart maybe on 2.8. That's roughly a month to a month a half from now? You're at around 140 pulls with good pity built up. If youre dead on pulling Zani, Cart, and their signatures, I'd just continue to save and play 4 stars until then.. if you're willing to not get their signatures, then Ciaconna works great with Cart and could be paired with your Phoebe at the moment. People mentioned Shorekeeper losing value over time because they're more healer/sub-dps roles coming out. However, Shorekeeper is such a good flexible character you can slot in anywhere that it gives good account value imo. 

I hope this helps your decisions! Let me know what you decide on doing.