I'm a big fan of WordPress - http://wordpress.com/ I use it for my own blog and I administer three for my church with it. Mine is hosted by them at .com, the church blogs are hosted on our own server, using the wordpress software downloadable through wordpress.org I fully admit that once I was satisfied with WordPress, I stopped looking at alternatives.
I originally started on Blogger, but moved away pretty quickly. That was a couple of years ago and it may be better now. Have heard good things about Typepad, but no direct experience.
