Reed can play FS well, so it is a legitimate question. They are very similar players in that they are intelligent, have pretty good speed (Reed's a little faster), and can hit like trucks. I have always liked what they bring to their defenses, especially Dawkins because he is one of the best leaders in the game today. Reed would be the leader of the Baltimore D as well, but that is Lewis' job. If you watched Reed ath the U you know he is a great leader.
I give Dawkins the slight edge over Reed, but in a few years when Reed is in his prime, he will be a better player then Dawkins' in his prime.