There’s nothing quite like an upgrade which is easy, seamless and gives a whole bunch of new features. The WordPress 2.0 upgrade was like that. Nice. I’ve also switched from the WordPress default theme (which I used for an embarrassingly long time), to the nice and modern K2.
I would certainly like to use a TurboGears-based blog, but I tend to be more practical than that. WordPress gives me a lot of great blogging features with a giant community supporting it.