Stopped Gore Al Would
I believe 9/11 would have happened even with Gore as president. This event took place relatively early in the Bush administration. He hadn't really done anything to anger the world other than follow what the previous administration had been doing. Clinton and Gore together had bombed other countries, they were very active supporters or Israel, etc.
However, if Gore had been president, I think the response to 9/11 by this country's military and government, would have been much different.