Fire Emblem Fates is indeed very bad story wise, but I liked the fact that both sides can use pair up.
C'mon bro you're playing the "Have Avatar is bad" like people play "Have a sword is generic", at least give a chance to the new Avatar, I think he will not be the main focus, he will be more present than Mark for sure(since for what I know you can do Eliwood history WITHOUT the tactician) but maybe he will have a Kris/Robin presence, being the right-handed man for the lords, but also killing everyone that gets on his way.
Also FE7 the best written? yeaaaaaah... no, that I would send to Genealogy of The Holy War or Tharcia 776, or maybe even Path of Radiance! FE7 have a awesome history but I would put him in top 3 for sure, but Genealogy is simple another level for me, in Genealogy case almost every problem I can see that is hardware relacted, that a Remake on Switch would make be almost perfect.