Personally, I would go for the Celadine, since it is much more tolerant of our cold wet winters if it does rain often in winter. Anyways, if your parameter of choosing is just based on scent..either one should do. But I would really caution you to consider more its growing area preference.
Though I have not grown Singapore White Plumeria, anytime it is a Plumeria much more accustomed to a more hot humid environment, I would think twice growing it here in our low humidity Cali weather. Unless you are in the coastal side of SD, then you may have a better chance. Good luck!