Before we can give you a definitive answer to that, we need to know the year you are talking about. There were a BUNCH of trails, as others have pointed out, but they were not all around at the same time. For example, the Smoky Hill Trail that rambam99 mentioned was mainly developed during the Colorado gold rush; before that, people mainly (but not always) went to Colorado after leaving the Santa Fe trail at Old Bents Fort. Give me a date, and I'll see if I can give you more info.
BTW, the Smoky Hill Trail was not an easy one to find or follow, as the Blues Brothers from Missouri found out. Could be called "cannibalism on the trail!"