Anil Dash has written an article titled “A WordPress 2.5 Upgrade Guide” on the official movabletype.com blog. It is full of misdirection, and, thankfully, overall it hasn’t been well received. What excites me is it has sparked some excellent discussions, and it’s a great launching point for more conversations.
I whole heartily recommend you try the open source flavor of Movable Type. It is clearly a great product created by fantastic people.
If you are thinking you only have time to try one other blogging software than WordPress, my time and money is on Drupal. People bringing Drupal into the conversation as an alternative has been one of my favorite parts of the discussions. Built on the same PHP stack that powers WordPress and much of the rest of the high performance web. Drupal is the full featured CMS with the heart and minds of the open source communities (I hang out with). Its blogging experience isn’t as polished out of the box as WP or MT, but it’s getting there — and we’re working hard at staying focused and one step ahead of them 
If you have time please do share what you love about these other personal publishing environment, particularly if it relates to something that annoys you about WordPress. This way WordPress participants can respond by letting our code do the talking.
If you are currently using WordPress then your highest priority will likely be to plan to take a look at WordPress 2.5 as a release candidate will be coming very soon — watch the WordPress Development blog for the news.