I really really like the short/game version of P4's "Pursuing my True Self", the title is something like that. All the syncopations are right on! The bass is so nasty, the changes are hip, the horns are hitting the right spots and the vocals are so :3 hehe.
I really like any of the vocal ones from P3 and P4, and the P3 song when you take the test, it's so catchy. I never heard a music before capture the feelings of taking a test in school in an interesting way.
A lot of the instrumentals are cool and creative, lotsa weird synths and things, not usually music I'd listen to out of my own choice, but when it's in the game it's perfect.