I'm going to be the minority
Aedan fan again (I think there was another member that liked this spelling too but I forget who). Honestly, this is the spelling I grew up with and
Aidan looks slightly weird to me. Still, I would probably default on the
Aidan spelling because most of the Aidans I have met spelled it like that (I think I came across one that spelled it
Aedan and I was pretty happy). I would use
Aedan as a first or middle name (though I have favorites above it) and granted, that spelling isn't as popular or made up like
Ayden, it's a saint.