I am searching for a blog-service allowing several subcategories in the menu. I seem to be too inexperienced finding them here... so, at first, let's check a list of some "top" (?) blog sites, according to:

• Blog Services Review
• Bloggers Choice Awards

To put it simply, people recommend WordPress for maximum functionality. Several other blogs for beeing fast and user-friendly, for example blogger.com.
Here you find some hints for free blogs, and in this link you find some top ten lists for thematic blogs.

Someone explaining it all. :-)