I've tried arimidex, aromasin, and letro and letro is my favorite hands-down.
I am extremely prone to gyno, aromasin doesn't prevent it for me and arimidex gives me erectile disfunction.
Not only did letro get rid of gyno lumps that I had for 3 years, after enough experience using it, I've found the perfect dose where I can maintain libio and completely eliminate gyno.
I buy the liquid version, sterilize it with 3% BA, and inject 1mg weekly so it's extremely inexpensive.