You may basically use your Facebook Notes and Google + to blog.
But the top 2 most used blogging site is WordPress and Blogger.
Pros: Ease to use with little you can mess up.
Cons: Less customization and a bit fussy with adding certain features.
Pros: Publish anywhere, huge community, images, video, edit HTML/CSS, template designer, track traffic stats in Blogger, Adsense at no charge
Cons: While Blogger is where many writers (including Dear Blogger) started publishing, it’s designs appear a bit childish today. Google owns your blog – they axed Reader – so acknowledge a bit less control upfront.