Best thing to do is (providing you have the time) is to setup a test blog with each script you want to try and see if you like how the templates are, the Admin section, and if it gives you features you want. Take a couple days with each one and try it. Scripts I suggest are WordPress,
Serendipity Blog,
bEvolution,
MovableType (although this is fee based)...there are others too but peeps here will probably add more to the list including their user opinions. You can also check out
Hotscripts
lots of choices
