Just in general terms, for general water retention, bloating, gyno prevention, which is better? Aromasin or Arimidex?

Is one better or more effective than the other on cycle?

The question is just in general terms. I am on a Test/Tren/Mast cycle and have been advised by some that I should be taking Arimidex and others say it should be Aromasin (which I am).