Largest and most reliable platform for blogging (free) are wordpress.com and blogspot.com.
WordPress.com is probably the most easy to use with a friendly interface and easy to remember. It is well optimized for search engines. For someone who is starting out in the blogging world wordpress.com is a solution exceptional.
But keep in mind that in wordpress.com does not allow scripts us histas or adsense. The ideal solution would be wordpress.org, but is not free. You need a domain (.org, .info, .net, .com .... - with money or free .co.cc, .tk, or other), and a hosting (web hosting) paid.
Blogspot.com is a blog solution offered by Google. Although many might think it is better indexed, wrong. In wordpress tags offer superior indexing, which can not speak in blogspot. In blogspot tags are only good for use as categories, so.
But the beauty is that Blogspot allows you to do almost anything. Any theme compatible bought with money from online or found on various websites of free profile can be used with ease. With minimal knowledge a blog on blogspot platform can become a true portal. But the most important thing is that Blogspot bloggers allow insertion of the scriptures, and in the interface of blogspot is even Adsense..