Which of these units should I promote to five star?

I'd say either Eirika or Cherche

Frederick or Cherche. They are amazing Green units. Eirika is good, but she needs +Spd mainly to survive longer in her role as a buffer,

Assuming your a f2p player or close to it, it depends on the units you have. I would promote Eirika unless you have Ephraim already(but you relatively want to have +att or Spd on her). If you do, wait. I would keep Frederick, Cherche, Adult Tiki, Est as 4 stars because of merging potentials. Also, those IVs are pretty bad for Est. You would ideally want +att on her. The rest of the units are not worth those feathers.

I’d definitely pick Cherche