This has been percolating for some time-- since I got my hands on the new Akaneia artbook, really.
If you had to pick one "hero" for Fire Emblem: The Sacred Stones, which twin would it be? I realize the natural answer is, "They both are!" but bear with me here. If you needed to pick one single represenative for the Magvel saga, whether for purposes of discussion or for inclusion in a Dissidia-style fighting game, which twin would it be?
I think the side of fandom we're familiar with (herein called E!fandom because the common language used for fandom purposes is English) might choose Eirika. She's the first Lord character playable in the game. Her route seems to be more popular, or at least the one enthusiastically recommended to newbies. EirRoute appears to be the prevailing influence on the E!fandom take on supporting characters like Seth. And-- not inconsequential-- the female twin provides a bit of gender balance to make up for the male heroes of the other continental sagas (Marth, Celice, Roy, Ike).