Dyazide tend to be the most popular amongst competitive bodybuildersbecause it is a mild, postassium sparing diuretic. Dyazide works through sodium excretion. Since muscle tissue holds more potassium than sodium, bodybuilders favor Dyazide, hoping that the muscle size will stay, while they're dropping their water.
Out of the three, Aldactone, Dyazide or Lasix, I myelf would use Aldactone. You may get better results using one of the others but do yourself a favour, try them far in advance to your show to see which one you prefer. Don't make the mistake of doing them at the last minute and not knowing what you're outcome will be.