Which one do you use? I use Wordpress. I have found wordpress the most SE friendly. Plus the fact that there are more plugins for it than any other blog script. There are also more free yet good looking templates for wordpress. But I have to say that by far... the admin panel is very simple and advanced. I just think that all around it is the best. While other blogging scripts might beat wordpress in some sectors... overall WordPress rules.
But thats enough talk from me. What do you guys think?