LogFAQs > #980272420

Birthright has a decent story and mediocre gameplay, Conquest has amazing gameplay but an absolutely god-awful story, and Revelations attempted to balance between the two main routes but did a bad job and makes the worst parts of each one stand out more. I'd say maybe play Conquest if you really like Fire Emblem's core gameplay and are willing to tolerate or skip the story for it. Aside from that, don't bother with the Fates trio at all.

If you were interested in Fates for the "waifu and eugenics simulator" aspect, FE Awakening did that several times better, so go play that instead.