When I first started tinkering with hosting blogs on hoeben.net, I thought it would be a nifty idea to base it on phpBB. One of the sites I visit regularly is myHTPC.com, and I liked their idea of the whole phpBB based 'portal'; everything that happens on the front page comes from somewhere in the bulletin board. Different authors have different (moderation) rights, and the whole thing looked pretty spiffy to me.
Toying around with phpBB I found out that it just wasn't ready to do what I wanted: have a number of differently styled weblogs, and have them aggregated on a main page. Sure, with some hacking and slashing, it could be made to publish rss streams, and have different parts of the system display different themes. However, I found that creating themes was far too complicated, and tweaking the system to my liking was looking hard.
Then I stumbled upon Drupal, and liked it. I like how Drupal is a relatively robust platform, while it is still possible to tweak the code here and there to add some features that are not yet available. Drupal has a lot which I'll never use, but I can easily turn it off/remove it. I guess I like rough edges here and there (as long as they are not in my panoramas)
Now should I look further? My girlfriend started a MT based blog just over a month ago, and frankly I hate it. Not her blog or the nice template she had me make, but the way MT works. It's probably due to the way MT is configured on the (free) mblog servers, but everything is rendered statically, and if we change something in the templates, everything has to be rerendered, moving all her content off the frontpage to the archives. And according to my girlfriend it just takes too many different clicks'n'pages to add content.
Now how is drupal better? Well, the source is not only open, it is reasonably accessible too. So sure, email submission is currently buggy, but maybe I will find the time to fix it, or someone else will. Oh, and rest assured, the theming on this site will changes soon enough...