Have been trying to compare these both apps since I got the macbook pro. Finally found a very detailed video to make an informed decision. This video by Todd Olthoff helped a lot to understand the major differences between the both.
After watching the video, I have decided to give both of these a try for a month to make the decision. Since I have already used Alfred for some time now, I am trying out Launchbar. It is quite good so far, uses probably a tad bit more memory than Alfred but it is hanging in there. I just bought the Alfred App :).
What is your preferred launcher app?