I've bred 2 Eevees; Modest Nature
-Eevee 1: Has 5 IVs HP, Atk, Def, SpAtk, Speed
-Eevee 2: Has 4 IVS; HP, SpAtk, SpDef, Speed
-Which Eevee would you evolve into a Espeon? and Why?
Assuming that both Eevee have the same nature, I would evolve the second Eevee into Espeon. This is because of two reasons:
I hope these reasonings help you decide which Eevee to evolve. :)