Assuming you are talking about the weathered daystar robe and not the upgraded one...

Both are perfectly fine for pretty much everything in the game right now. I use the Scylla's robe myself until we beat T7 and I manage to get a High allagan robe. Maybe consider using the one that helps you out in stats you are lower in? Of course if you already have the upgraded Daystar robe just use that, the MND increase will be more worth it as was mentioned.