A surprisingly well-kept secret is not a secret any more.
I was skeptical, since I'm a long-time user of BlogJet, but I'm very happy with what I've seen so far. The auto-configuration system is probably the coolest feature: it will post a test post to the blog to see what the formatting looks like, and can show you your post in the context of what it will look like on the blog (View | Web Layout and View | Web Preview).