I've switched from the old free version of Movable Type to the less glitzy but highly popular Word Press. So far it seems easy to use, and it imported all of my old entries, comments, categories, links, etc., so I'm happy that it was so easy to install and set up.
I'm using the default theme (stylesheet) right now but will of course have to style the site myself once I get things set up, figure out what I need/want to change, and adjust to the new software.
I like it so far, though. Hopefully I'll be able to write a plugin (a major advantage of WP over MT is that the former is written in PHP) to stop comment and trackback spam.