Ultimately it doesn't matter since you can unlock everything on one character. You would've been able to start in Gridania and still become an Arcanist. Also you can choose any GC you want so you can still align with the Adders. The starting city is just that, a start. For myself, my story is that I am the son of a Lominsan merchant who went to Gridania to study Conjury (since that's the only healer you can start as, when I was new to the game). This allows me to have a start in both cities, "technically". Why not just reverse it for yourself.