I've been using MarsEdit for a while now, because of its dead-simple design and markdown integration, it's a great tool for quickly composing blog posts when you don't have a network connection or don't want to use a web-based form.
In case you hadn't heard, MarsEdit was recently acquired by Red Sweater Software and they have been starting to issue minor updates and fixes. The recent release features bug fixes and (woo) Blogger support, but I'm mostly looking forward to the addition of drag-and-drop images with uploading (fingers crossed).
I tried ecto a few times, and found it clunky and a little complex for what I needed to do—just write a blog post. If you hadn't tried MarsEdit before it's probably worth checking out.