The picture really says it all in terms of the statistics from Pingdom recently calculated:

Typepad, Blogger, and Wordpress.com are the most reliable and blogging services available.

Make sure to note that it’s Wordpress.com and not self-hosted WordPress.org. Read more about the comparison and findings here.

From a strict usability, customization, and overall kick-butt-ness… Wordpress is the hands-down winner in my book.

But you knew that already.

All in all, if you’re not using one of the top 3, then you should probably consider moving.