I still like Class Blogmeister, particularly for schools where filtering and confidentiality concerns pose potential roadblocks. You might try it out for yourself first and see what you like and don't like. It has a very plain layout; you can password the page so no one but approved users can see it if you wish; students do not need e-mail accounts to use it; teachers find it easy to use.
In the states, WordPress.com is not always an option (it's blocked in my district). I'm trying to find out if we can install WPMU on district internet server, if not, edbulogs is a better deal than paying hosting fees for me. There are few platforms that are open, we have a legacy block on classblogmeister left over from the days when ALL blogs were blocked, so that would leave 21 classes which is currently free, but hasn't been updated supported in ages. I'm happy to spend $40 a year for edublogs. Getting threaded comments has made improved the whole blog commenting thing a lot, and is worth it to me for that. EVERYTHING is slow at my school/site district at this point. I don't find edublogs too bad at home where I have a better Internet connection. I haven't gotten to the point of student blogs yet, but that will start by the end of the year. I will also be doing blogging with another school in a nearby district soon. Should we move this convo to forums so other can participate.
Sometimes it can be slow... If you can pay for the ad-free version, I would really recommend setting up a school install of WordPress. I think in the long run it's a much more sustainable and functional option. But, of course that depends on how your tech support is structured :) Our school has a WPMU installed and it's fantastic!
Sadly, I have to say I would probably go with WordPress - either WordPress.com (the free online editor) or your own installation.
Edublogs was absolutely perfect when I started out - it provides a great community and I so appreciate all the work that James Farmer has done to help educators start blogging.
However, with the recent changes in service agreements (ads on individual blog posts for free accounts), I'll most likely be switching to my own installation of WordPress sometime in the near future myself.