AIs. There are 3 ais - anastrazole (arimidex), Letrozole (femara), and Exemestane (aromasin). All show similar clinical benefits in clinical trials. Some patients will tolerate one better than the others but there is no way to predict which one. Other hormonal therapy options include tamoxifen, toremifene, and Faslodex (fulvestrant) (an injectible) but none are particularly "more effective" than an ai.
Somehow? Probably need to restate this.