Which blog to choose?

Interested in the following topic - in the internet there are more and more diary services and it is becoming increasingly difficult to choose where to maintain your blog.
It's a shame when you start blogging in a rather promising service, and then it fades out.
To work, you need to maintain a blog in one area, for relaxation, communication and dating in another. What factors should be considered when choosing blogs?

Who solves this problem? Importing posts to various blogs, maintaining multiple blogs at once, openid?