I currently prefer Launcher Pro for two main things. First is the dock. I like having as few homescreens active as possible, so it's nice to have my five most used icons sitting down there on the dock. That leaves plenty of room on the main homescreen for my clock and weather widgets and other most used icons.
The other thing I like is the widget skinning that was recently implemented. I use one homescreen just for the Gmail widget, and another just for calendar/agenda. I like the Sense versions of these widgets, but I love that the LauncherPro versions have so much variety in how I can make them look.
A third thing that I enjoy is the swipe gestures on the dock icon. The only one I really use is the bookmarks swipe, but I love that it frees up a homescreen that I now don't need to use for a bookmarks widget.