For me, the switch from Movable Type to WordPress was a good one. As my blog had grown significantly in size since I first migrated to MT, I was growing very tired of how long it took to build. A full website build with MT could take five minutes or more (sometimes, a lot more). Even a single page build sometimes took 15-20 seconds.
I hadn't check out the MT website for quite some time, but I just noticed that they released MT 3.1 on August 31. The new features that would appeal to me are:
* Choice between static or dynamic page creation
However, these are features that WordPress already has. Well, WordPress doesn't offer static page creation, but that's a feature I don't want anyway.
The biggest MT advantage, IMHO, remains the rich set of plug-ins that are available for MT. WordPress can't really compare. While it sounds like MT offers a very rich API for developers to work with, I can't compare it to the WordPress API, because I have not written plug-ins for either platform. If MT or WordPress were written in Java or Python, I would be much more interested. I don't have time, or a desperate enough need for my own plug-in, to learn PHP or Perl.
Given all that, my reasons for choosing WordPress over Movable Type are:
1) I'm an open source developer and am naturally inclined to prefer open source tools (i.e., ones that use licenses like the Apache license, CPL, GPL, LGPL, etc.)
2) I'm not a plug-in collector or fanatic, so the smaller supply of plug-ins wasn't that huge of a factor for me (though there are a couple I miss)
3) For my blog, WordPress handles spam comments better than the MT Blacklist plug-in. The new anti-spam feature is MT 3 is alledgedly better, but it didn't look significantly better to me.
4) Blogging is a very part-time activity for me, so I couldn't justify spending a lot of money on the software. I would rather spend the money on donations to open source software development projects.
5) I also run a blog for a non-profit, and at the time that I made my decision to go to WordPress, it looked like upgrading to MT 3.x would not be cheap for the non-profit. They have less than 5 paid employees, so I would have to ask MT about their special pricing.
6) I would like to set up a couple of blogs at the start-up where I work. Cost is a significant issue, especially since I'm not sure how frequently they would be used.
I still think that MT is a great product and the people at SixApart seem like really good people. I think they received a very good, albeit tough, lesson in marketing and public relations. If I were more serious about blogging or were more interested in hacking on Perl-based plug-ins, I probably would have stuck with MT and paid the $70 license fee.
As for a blow by blow comparison, I think the comparison at Neowin.net is pretty dead-on.