The A is wrong to me. It has sad in it. I think of
Isadora as a glam antique spelling, a naming-after
Isadora Duncan. Sort of like
Edythe. So
Isadora is just okay.
Isidora, though, is really nice. I think it would end up with a nickname if it were my daughter -
Izzy or
Dora or
Dory. I really like
Dory a lot, too.