I like them both fairly well, but of the two, I like
Paul the best. Because the New Testament Biblical
Saul changed his name to
Paul when he turned his life around, I tend to associate the name
Paul with redemption and the willingness to give a second chance.
Saul sounds a little stiffer and more like a pharisee. I have known a few Pauls who were nice fellows, but I haven't actually met a
Saul so perhaps that is why it doesn't leave as friendly of an impression.