I prefer
Delia to
Dalia.
Dalia /
Dahlia sounds so pretentious to my ears. It reminds me of snooty people saying darling as "DAH-ling." Or are you pronouncing it more like "DAY-lia?"
So, are you going to use
Dee as a nn? I knew someone once named
Deirdre who went by Dede. I think that's a cute nn and I prefer
Deirdre to either
Delia or
Dahlia.