The only "cure" for ED is improved diet and exercise. However, only a few with mild ED caused by circulatory issues can take advantage of the cure. I have severe diabetic induces ED and have tried all the Big Three and found Viagra worked best for me. However, each guy and condition reacts differently to the different pills so you may need to test each to see which works best for you.
Unfortunately, my ED has reached the point where even 150 mg of Viagra no longer is effective so I now need to inject Trimix in order to achieve an erection.
Note: the above refers only to guys suffering from true physiological induced ED. If you are suffering from temporarily reduced EQ, a good PE routine should do the trick.