Id tend to agree with Dr. X in regards to Lasix being more dangerous than the others. I would suggest giving Dyazide or Aldactone a try before Lasix. Lasix has got a reputation for being quite harsh on the body and potassium robbing. In reality though, Dyazide , at large doses can be potassium robbing too.
Aldactone is the weakest of the prescription diuretics. As a mild and potassium sparing diuretic, it is especially popular with female bodybuilders. I've used it and I find it works quite well for me, being female.
There is also Aldactazide. This one combines Aldactone with a thiazide diuretic. This is a lot stronger that Aldactone.
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.