Miu and Tsumugi are my favorites. Kokichi and Shuichi suck. I would've liked the game a lot more if Kaede survived (killing off Shuichi in the first case would've been cool too). I think case 1 and 6 are really good (6 might be my favorite in the series), but 2-5 aren't that great.
All the stars in the sky are waiting for you.