Writing a blog can be fun and satisfying on its own, but having an audience makes it even better. The question is, how hard do you have to work to find your audience?
Blogger has a Blogs of Note page that shows links to blogs in a format that you can choose, with a seemingly infinite scrollability, and a search box to narrow the field. You can get to this page either via a link from the login page or by knowing the address of the page. I was unable to find my blog here.
Once logged in, the only access to other blogs is either through the All blogs link, which doesn't seem to work; the Add button, which allows you to add blogs from a URL or from Google Reader; or through the Next Blog link on your own blog pages.
All of the above indicates to me that there is no built-in audience at Blogger if you're not one of the chosen ones, so you have to advertise your blog yourself via other methods.
Tumblr gives you access to blogs via your main dashboard, by clicking on either Find blogs or Explore Tumblr, or by entering search tags in the search field.
Find blogs takes you to the Spotlight page, where you can explore spotlighted blogs by category.
Explore Tumblr takes you to a page that shows popular tags that you can click on to see related posts. The automatically scrolling pictures at the top give access to the categories with the latest posts. As you can see from the screenshot, I caught it in mid-scroll. This page is pretty active.
Entering a search tag takes you to a page that shows you a stream of posts that contain that tag. This screenshot shows a search I did for "technology".
When someone likes or reblogs one of your posts, a note is attached to it. You can see notes on your blog's dashboard interspersed among your posts. This visible feedback makes me feel part of an active community.
WordPress has a Freshly Pressed page, where you can see a selection of posts and access either the individual posts shown or the categories related to them.
There's also a Reader page where you can explore blogs by topic. The search box allows you to search by any keyword you enter. I was able to find my own posts via the search method.
After publishing a few posts over a couple of days I found I had acquired several followers. WordPress sends you email every time someone follows your blog or likes one of your posts, and also puts a note on your Notifications page. This kind of feedback definitely gives you that warm fuzzy feeling.
For the visibility of my blog on these sites, I rank them as follows:
The Free Blogging Site Experiment
The Blogger Dashboard
The Tumblr Dashboard
The WordPress Dashboard
Blog Appearance Comparison
Blog Posting Comparison -- Styles, Tools, and Ease of Use
Blog Activity Tracking Comparison
And the Winning Blog Site is ...