By “free blogging platform,” I’m assuming you mean one that’s on a free hosting solution (like Wordpress.com), as opposed to one that’s self-hosted (such as Wordpress.org).
Personally, I use Wordpress.org—although Wordpress is free, I have to purchase a domain to use it on.
Anyway, I digress. I guess you’re talking about the totally free Web 2.0 platforms. There are a number of them.
Tumblr, Blogger, and Weebly come to mind. Those are probably 3 of the best (though opinions vary).
Having said that, if you’re looking for totally free solutions that you don’t have to host on your own, I would encourage you to consider self-hosted solutions.
Having a domain of your own means that you don’t have to worry about your content being removed. (Of course, your hosting company can disable a domain, but those are under more extreme circumstances.)
If you originally meant that you had your own self-hosted Wordpress sites, but want to try something else, I’ve heard that Drupal’s pretty good, too.
And to completely answer you, as far as I know, a self-hosted Wordpress blog is as good as it gets: the general IM consensus is that there are soooo many plugins and ways to enhance Wordpress that it's usually a far superior option to anything else.
Hope this helps.