I can sum it up in one word “Security” I have never had a MT install exploited. Cannot say the same for WordPress. I missed one of their frequent security updates and my mom’s blog got exploited in less than 2 days after the security patch was issued by WP.
I also run all of my blogs from a single control panel. One MT install drives all of my sites. I have nearly 20 blogs all running from a single control panel try that with wordpress. Thus when their is a update I update a single installation and I am finished.
The Movable Type editor also simply works, when I use an external editor like Blogjet as I am now. I know that when I hit publish the the way I have typed it in the editor is going to be the way it is displayed on my blog.
WordPress is nearly impossible to work with in the templating department. But the MT templating is very simple and it is very easy to make changes, great for novices that want to have a website that looks like their own. I get sick of seeing all of the cookie cutter boring design that make up a large number of WordPress sites.
I run both MT and WP blogs, and I will say without reservation that while I have given MT grief in the past for some of the things they have and have not done. I can say that the MT platform is much more stable and it handles heavy traffic loads a lot better than WordPress ever will. SixApart
Note: This may sound hypocritical but for people just starting a blog that only need a single website WordPress is a good choice. I have stated on this blog that I would only recommend wordpress and generally that is the recomendation I give people. But I do add my concerns as listed above. For me though, and the way “I” run this site MT remains my only viable choice.