M: Got a perfect eevee in Pokemon go. Make argument for which evolution to choose?

G: Nice find. The best Eeveelution depends on what you want:

PvP (Great/Ultra League): Umbreon (tanky, strong in Great League) or Glaceon (decent in Ultra League).
PvE (Raids/Gyms): Espeon (great Psychic attacker) or Glaceon (solid Ice attacker).
General Use: Sylveon (bulky and versatile) or Umbreon (best for defense).
Rarity/Flexibility: Sylveon (harder to get), or just evolve based on your favorite.

If you want pure power, Espeon or Glaceon. For utility, Sylveon or Umbreon.