1. Norn9 - <melee> (vocal: Nagi yanagi)
It's a comfortable song that makes me feel like i'm in heaven.
2. 蝶の毒 華の鎖 - <心空-kokorosora-> (vocal: Miu natsuki)
The sad and desperate vocals of this song were excellent.
3. 女王蜂の王房 - <砂の薔薇>, <堕天の戀> (vocal: Rita)
I think it was a grand song that represented the world view of the game very well.
4. Mystic messenger - <Mysterious Messenger> (vocal: Han)
The accompaniment at the beginning of the song captivated me.
1. Jack and Jeanne of Quartz (Jack Jeanne), got me seated for the rest of the game :)
2. Lycoris no Ai (Virche Evermore), I have been listening it since I found it. Even more when I saw in translated interviews that (major spoilers I think) it was made with Ankou in mind!
3. Tatoe tomo ni (Olympia Soiree) I think it is one of the most beautiful OP themes and I listen to it often :)
4. this one is from a mobile otome: Anata wo tada aishiteiru (Ikemen Prince), it is very beautiful and romantic meant for me to shout my heart beneath the shower lfdjhsdklf
other OPs I like: "Floatable" (Code Realize), "Some song I forgot" (Taisho x Alice) and its variants (specially the one for part 3, very intense dkjlgsg)
I haven't played Cendrillon PalikA but, the OP ("Cinderella Story") is very fun to listen :D
The first thing that comes to mind is the OP "Let's dream, let's pretend" from the Taisho X Alice series — it's incredibly good.
Although the OPs in each part are somewhat similar, the musical arrangement is different.