Sakura from Edelweiß (and Edelweiß Fantasia in which she plays a major role instead of only a side one), personality-wise she is one of the most attractive girls in the games I've played so far, especially in combination with the male main character, Kazushi.
Also, Kazushi himself, he's just a really funny person with a likeable personality.
Kirara from Yumina the Ethereal is also one of the more remarkable chars I've seen so far, due to her being one of the few characters that are fully included in the story while being way stronger mentally than the complete rest of the cast. Usually, characters like that are forced to play minor roles because they can break the story balance far too easily with their wits and abilities. In fact, she continues to force trick the rest of the cast into furthering her own far reaching plans while making it look like she's doing them a favour with it. She's pretty much the driving force behind most of the story. Which is great, because she's your ally. Very well executed character.
These are not all of my favourites, the complete list would take a while
