1Ne 7:10 How is it that ye have forgotten that ye have seen an angel of the Lord?

The manifistation of the Holy Ghost in the heart has greater effect on a persons life than the manifiestation of an angel.

Think back in your life. Think of a time a parent reprimanded you and you knew they were right and now think of how you felt, the guilt, the healing, the peace and then the joy. An angel is a messanger and would be like the parent reprimanding or telling you something new but the holy ghost is a message or a reprimand from within and the Holy Ghost does not leave you there like the angel would. It is there to help you heal, to feel for what you have done wrong, to feel peace and joy and ultimatelly change into a better person a little at a time.