WordPress and Blogger are hands down the two most popular blogging platforms. I honestly see no reason to consider any of the others.
I started with Blogger, but when I started learning about the flexibility WordPress provided, I switched over in December 2007 and I'm so glad I did.
Blogger is great because it's super easy to use. However, WordPress has a lot more features and plug-ins that will allow you to enhance your blog.
And even though setting up a WordPress blog is slightly more involved, it's well worth it in the long run.