Slice: Bloomed Baccara is apparently OP. Aside from that, Bride Oncidium for the same reason as Cherry, or Alpinia/Kerria for her life drain.
Pierce: Daisy bias incoming. But Daisy has a great bloom and not much competition, anyway.
Magic: Tough to say. Ardisia has close to Dendrobium levels of TP, but most of the magic girls don't have anything remarkable among rainbows, off-hand.