Why not just spell it Olivia? A different spelling doesn't make it unique and can just be annoying for the person whose name it is. My name is Staci and it's annoying always telling people "stacey-with-an-i" and people still get it wrong. She's always going to say "Alivia it's like Olivia but with an A" and people still won't get it.

It’s spelled Olivia, so just spell it Olivia

Olivia looks prettier than the other 2 spellings

I’ve considered Alivia, since that’s how it’s pronounced anyway. It changes the pronunciation in Spanish though so that matters to me. I prefer Olivia for that reason but Alivia is ok too