I tend to pronounce
Arianna AIR-ee-ANN-uh, and
Ariana AIR-ee-AH-na. But I think I've also heard ARE-ee-AH-na, which seems to me to fit
Ariana. I prefer
Arianna because it's a dear friend's name who I would love to honor. She pronounces her name AIR-ee-ANN-uh, but occasionally has it mispronounced. She often goes by
Ari. I also think the name is lovely in general.