If you are reading this, you probably are just coming into the blog world. Welcome. One of the very first decisions you must make (aside from a name & topic) is what blogging platform you will use. There are many services- Blogger, WordPress.com, self-hosted WordPress (aka wordpress.org), Tumblr, TypePad, and many others.
WordPress.com is a great service to use because it allows you to manage posts and stats great with its integrated tools. It is also good because if you ever decide that you would like to switch to a self-hosted WordPress (it’s open source), you can export all your posts to it. WordPress.com’s main shortcomings are that it does not allow Google Adsense or Analytics. Both of these, however, work in the self-hosted version of WordPress, which is really the best option because it is fully customizable with plug-ins and, well anything.
Self-hosted WordPress is certainly the best platform, without a doubt, but you will probably need to use a paid host in order to get satisfactory performance. If you just like blogging and are doing it for fun, use Tumblr. If you want to make money, but don’t want to invest any, use Tumblr. If you want as professional of a blog as possible and you don’t want to spend or make money, use WordPress.com. If you want a professional blog with lots of plug-ins, ads (so you can make money), Google Analytics, and more themes/customization ability, install WordPress.org on a paid server. (I like FatCow– they have an auto-installer.)