I’ve worked with a variety of the blog hosting services here’s how they net out:
Typepad – Professional site for blog integration with web sites, more difficult to use in creating a professional design, easy adsense plugin and other blog widgets easy to use. Traffic refferrers only available for past 24 hrs. Some comment spam happens, but I get email alerts anytime anyone makes a comment so I delete them myself.
Blogger – Easy to set up, and has better publishing tools than it did a few years ago. Adsense is easy to setup on it hence the google ownership. Can be integrated with your other google accounts to manage all together. Its spammy though. Spammers & sploggers looove blogger.
Livejournal – More about personal blogging that media, news or publishing. You can syndicate all the feeds you read to your freidns page and read them all in one feed. Few tools for formatting, most people know code to modify designs. Never had any comment spam there. They have a new site VOX also out now.
MySpace – Haven’t been on here in a while. I hear its the hot happening spot fo rock bands, teens and well, people who prey on kids. I tend to stay off this network because its got a lot of garbage on it and a lot of people contact you through it that you don’t know.