If you want to set up a personal blog, or a non-serious, non-business blog, by far the simplest way is to sign up for one of the following sites:
Business blogs are definitely worth setting up as a self-hosted WordPress blog on your own custom URL (i.e. yourname.com – rather than yourname.wordpress.com). This takes a bit longer to set up – and you’ll need to stay on top of updates to the software, themes, plugins etc.
If you’re happy with a blog that’s hosted on one of the above three platforms, they offer the fastest way to set up a blog.