I personally love Blogger and Tumblr.
Blogger - I like the features on it, and how the stats and traffic information is recorded so you can view it later.
However I found that I haven't been very successful with traffic on this site.
Tumblr - I love the community on there. Tumblr users always refer to us as 'one big family' and I definitely feel it. You get to connect with people from all over the world. So far I've interacted with others my age and who share the same interests and likes. Everyone seems very friendly.
Also, I love that Tumblr has hundreds of layouts (called 'themes') to choose for your blog, and there are so many ways to customize it to your liking!
I actually wrote an article on the reasons why I love Tumblr. It would be on my profile - feel free to check it out if you like :)