Obviously I've used Blogger exclusively and have found Google's security features, comment moderation controls, easy to read stats, customizable domain names and even access to stats well worth the time I put into setting them up. I love that you can set up as many of the best-looking blogs you want with one account! Here are a few platforms you may want to play around with.
ePals Global Community: Connect with nearly a million other classrooms in over 200 countries. In addition to email buddies, literature circles, collaboration projects and explorer expeditions, epals offers CCSS supporting resources for multiple grade levels.
With Kidblog, teachers can log in with their google accounts and be ready to blog in minutes. Here's one I set up as an example. Very simple format and a few cute designs to choose from. It's a not a bad idea to start to see if you like it better than Blogger.
Edublogs' basic blogs are also free and more user-friendly for younger children than blogger because they're designed especially for teachers and students. Unfortunately, a paid membership is required if you want to post videos and html, make accounts private or have a custom domain name.
WordPress, a popular open source platform, gives you the option of setting up an attractive blog or website on your own server (for free) or creating a WordPress-hosted one at WordPress.com.
Typepad is not free but, according to PC Magazine, they produce the best-looking blogs around. You can choose a 14-day free trial to see if it works for you. While I haven't personally tried, they've apparently earned a reputation for great support and ease of use. Like Blogger, they also have a reliable anti-spam comment feature, which makes it a safe option for students.
21 Classes used to be free but is still affordable so worth checking out for it's ease of collaboration. Teachers can create accounts for their students with stories to read and/or comment on those stories.
Please let us know if any of these platforms have worked for you or if you find others worthy of mentioning!