Unless you are a well known columnist or humorist who is selling a book, blogs that take the form of a rant are usually not recommended for a business blog. The structure of this type of writing usually reads like therapy to other readers. If you want to or froth at the mouth about your favorite controversial then you are much better off to write a personal blog. Not that there is anything wrong with personal blogs, its just that the rant is not a particularly effective business marketing tool.
Rants can work if they are liberally sprinkled with effective keywords. One way to write a successful rant on a business blog is to sift through news stories, articles and informational products about your theme or topic and then write a response or your own insights to the �news.�
Also, if you are too emotional on a blog you might discourage others from responding to you. This is because they may not be that enthusiastic about leaving any pings back in case you attack them personally. They also might get the impression that you will remove any opposing points of view form the blog. This is a bad impression to leave as pings (responses to your blog) are a valuable source of natural SEO content on a blog.