If you can't tell yet, Colombia is our absolute favorite country that we have visited so far (we are currently in Ecuador, so we haven't gotten much farther). This is not to say that all the other countries we have been to are awful. To the contrary, we've loved our time in every place, and each one is unique and enjoyable in its own way. At the moment of writing this, we have driven from the US through every country in Central America and into South America, and it has been amazing. But Tim and I both agree that there was something particularly magical about Colombia.
One of the greatest things about Colombia is a bit ironic. Because of its turbulent recent past, Colombia has not had the onslaught of tourism and modernization that other countries have. In fact, most tourists avoided Colombia for a very long time, and it wasn't until recently, as in the past ten years, that it really started to open up.