Avatars in general

Mary sue isn't a random insult stating a character is bad, it's a derogatory term to a character that is so idealized and important that the story is willing to bend itself to them (among other things). Mark is literally nothing. He gets talked at and complimented every now and then for getting through a map. Mark is such a non-element, he's the least noteworthy character in the actual plot and solely exists to be an actual avatar for the player. Hell, he doesn't even have a portrait to put a face to.

Kris is meh. He has no bearing on the overall plot, but his inclusion takes away already established ideas and character interactions from the original Mystery. He's the true hero, which the remake loves to establish immediately. Well, at least he's just some strong warrior. Kris was the first true attempt at an avatar, as well as set the grounds for IS completely ignoring the fact that a self-inset having a set personality tends to ruin the whole idea.

Robin went from a pretty inoffensive character that didn't really need to be an avatar at all to utterly ruining the final story of Awakening. They're a milquetoast yet enjoyable enough character. Nothing special despite being so beloved by Chrom and co. IS doubled down on the whole "self-insert with a defined personality" thing. At least they gave the excuse of amnesia to make it seem like "we" have missing history with Validar and such.

With Corrin, they missed the point entirely. When people said they hated that Robin stole the spotlight from Chrom, they did not mean that the new playable avatar should be one of the most detrimental elements to what could've been a good story. You can easily write a naive and good-natured main character without everything revolving around them. To make things worse, Corrin's personality and actions are so far removed from a no-personality self insert that he's not a self insert at all. Instead, he's a customizable protagonist named Corrin. I get what they were going for with the whole "Kris and Robin are the true heroes of the story" thing not being well received, but like Fates tends to do, they take an idea they intend to fix and somehow manage to make it worse.

An avatar character isn't and has never needed to be required for me to be invested in a story. I don't need to be friends with Marth and Chrom because I'm not part of the story. A customizable character in and of itself is a perfectly fine idea, but stop pretending it's me. Until I have complete control of every choice they make and every word they say, it will never be me.

To answer your question, Mark is the best avatar so far because he comes closest to serving his actual purpose as an avatar.

/r/fireemblem Thread