Microsoft Writer: the best, and possibly as good as a paid alternative. I’ve never been as happy with a MS product since… Notepad. Writer will remind seasoned users of Frontpage, while newbies will be right at home with the simplicity of the application.
There’s also the Flock blog editor, the built-in blog editor of the socially-friendly browser, Flock; and ScribeFire, the able Firefox plugin. It’s always a merry occasion when you have a blog editor right inside your browser, and ScribeFire even comes with useful options ranging from an inbuilt revenue-earning system and one-click posting to advanced pinging options.
But if you ask me, at the end of the day Writer wins hand down for its user-friendliness and solid synchronization.
Known quirks: many of the plugins for Writer (there aren’t really many, surprisingly) don’t work; others are plain scratchy. Among the ones broke are the ones made by the Microsoft devs themselves (not so surprising, eh?). Formatting often doesn’t agree either; take a look:
The original post in Blogger has a line break, which Writer fails to reflect. From my experience, I’ve had trouble synchronising posts with both Flock and ScribeFire. They also support fewer blogging platforms compared to Writer; and although ScribeFire in particular has some interesting features, both applications essentially feel like plugins, and lack the necessary MS Word-like seamlessness one would look for in a blog editor. [Update: I had just published this from Writer where the post turned out like this. I had to dig into the code -- a simple matter of tags getting mixed up -- to fix it.]