As pohnpei397 stated, this is largely a matter of personal opinion. I feel that, by the time the US entered the war, it was really the only option.
For most of the war, the US was happy to stay out of it (insomuch as we did not declare war nor provide troops, but we did provide supplies). Public opinion was pretty firm in staying neutral, and President Wilson was very staunch in his own anti-inflammatory policies, seeking to keep American interests as unaffected by the war as possible. He was constantly contradicted by former President Roosevelt, who was incensed by what he felt was a lack of courage on Wilson's part in this and many other diplomatic affairs. The sinking of the cargo/passenger vessel Lusitania prompted Roosevelt to remark that he was "disgusted with our government and with the way our people acquiesce" to its decisions. Despite the fact that he was no longer in office, Roosevelt enjoyed a strong public presence, and he might be considered the leading voice of opposition for the duration of our neutrality.
A great threat to that neutrality was German U-boats. It was in Germany's interest to torpedo any and every ship that it could; this would prevent supplies from reaching England. This, of course, would result in the deaths of Americans, and it was difficult for many Americans to stomach the idea of doing business with England and dying in the process, with no result other than a strongly-worded fist-shaking from our government. We repeatedly told the Germans that "unrestricted submarine warfare", meaning the destruction of any and all ships without warning, would result in a military response. The Germans acknowledged this but, as the war continued and they observed Wilson's ongoing pacifism, they began to doubt our resolve.
The final straw came in the form of Germany's official declaration of unrestricted submarine warfare, as well as the Zimmermann Telegram - a message from the German government to Mexico, encouraging Mexico to declare war on the United States and offering support if it would do so. This made it clear that Germany no longer considered us a real threat, and that peace could not be negotiated. Even if there had been no immediate ramifications for the United States, there would have been irreparable damage to our political power and reputation had we not acknowledged this provocation with a declaration of war; America would be seen as a country of pushovers, uselessly sacrificing its young men to the U-boats and begging Germany for mercy as they died.