There are lots of reasons to do this.  Check all that apply:

• You just want to spout about world affairs, or whatever else you care about.
• You want to practice writing regularly.
• You want a diary you can share with people.
• You travel and like to share as you go.
• You take a lot of pics and like to share.
• You don’t trust Faceplant with that stuff any further than you can throw a cheesecake under water.
• Other odd reasons I never thought of.

I haven’t tried anything but WP, recommended to me by the highly esteemed CJ Cherryh.  There’s Blogger, Blogspot, Tumblr, and more.  What I like about WP:

• It’s pretty easy to get started and figure out all the doodads.
• They make it easy to get a domain name.
• Customer service is friendly and honest.

What I don’t like, so far:

• Gallerys are a mess.  If the gallery gets screwed up as you are creating it, you can’t fix it; you have to delete all the photos and start again, losing all the captions, sequencing, all that other work.  We had that when I posted the Alaska pics.
• When you make a post, it puts up a sidebar congratulating you for the number of posts.  The sidebar does nothing useful, nor can you make it stop.  And if I try clicking on it, my browser crashes.  In the first place, I don’t need a brownie button for achieving 175 posts.  In the second, I like to be able to make stuff like that shut up.

If I were looking over blog software, I’d try the basics of all of them and then just keep the one I liked best.