Wordpress on your own web hosting. Seriously. I've used Blogger, Posterous, Tumblr and Wordress.com and pretty soon I find myself in a situation where I either need to pay for some basic feature (Wordpress.com) or not have access to that feature at all (Tumblr, Posterous). With my own Wordpress installation, I can install any plugin or theme I want and since I already have Webfaction as my hosting it doesn't cost any extra.
but aren't you paying for web hosting?
Yes but I'm already using Webfaction for other projects so I'm just putting it to better use.