Ada. Aida is fine, but don't use ayda - you'll sound like a stereotypical white suburban american parent trying to make their little one sound 'special' by chucking unnecessary Ys into a fairly average name
Ahhh thanks. I have zero knowledge of opera and want to avoid unnecessarily 'jazzing' up a name with unique spelling so if we go this way, it'll be Ada. It's just so short though, for some reason that bugs me.