I use Wordpress because it is the blog site that my domain host uses. I also really like it though.
I am currently on Blogger, but I plan to move over to wordpress or SOMETHING else a bit more versatile.
Blogger is great for the every day blogger, but if you want to launch into something bigger (which I do) - wordpress is a great start.
I would go to Wordpress.org too. From what I have heard wordpress.COM is even more limited then blogger.
I have a brother in law who is a web designer. He is helping me get set up and eventually we will do a full switch over to the new site :)