DBH (Discord/Black Hole) is a classic, but the Entropy pend version is more popular because it means faster Discord. Quanta control remains powerful against Plat though, so it should do fine regardless. Getting a fast SoFo is nice with Overdrive or Gravity Force, and especially against a low tower start.
If you want it to be more reliable against rushes though, I would recommend another GF over something else, although the truth is you'd want 4 SoFo and 3 GF to be truly reliable.