I honestly think both free blog sites are great but before creating an account in any of them, you have to think of what your blog aims first. Would you like your blog to be just a blog… like an online diary? Then chose Wordpress.com. They have a lot a really nice templates to choose from plus they have an excellent member support.

If you want to monetize your blog someday, I highly recommend signing up with Blogspot.com (this is considering that you are not ready to host your own blog). Why? Because Blogspot is the freeiest Blogging site. You can write sponsored posts without having to fear that your account will be suspended or cancelled. You can display ads from any PPC programs like Google Adsense, Bidvertiser, Chitika, and Widgetbucks. Blogspot.com allows you to monetize your blog while it is not so with Wordpress.com

Goodluck.