been listening to some of the D4DJ songs a bit more recently and read up some more on the characters and my current standings are:

• HapiAra remains my favourite group at least musically, although Rondo is close
• Tsubaki has strong oshi potential
• Lyrical Lily are SO CUTE I wanna say they're my favourites character-wise so far

no clear favourites just yet and I'm sure the anime will sway me in one way or another, but. Tsubaki.