Blogger.com
pros:
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1. easy to use
2. archives your entries
3. Lots of basic templates to choose from
4. Basic Blogger is FREE
5. Lot of people use it
cons:
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1. Security issues, giving them your FTP login/password for your site. Most people don't mind, some do.
2. For those who are HTML savvy, you can whip up a much better template for your entries than what Blogger generates. Because it's a loop generation, all entries are formatted in the same style, which is frustrating if you want more flexibility. I think Blogger Pro addresses this, but you pay for it.
3. The archive feature is hard to maneuver around. There is no search feature, and to find a particular blog can be painstaking since all you have to nav through are date ranges.
4. I don't think there are security features for your blog (i.e., password access). So, your blogs are viewable to all (I guess that's the point).