the best for hackers
I looked at lot of open source CMS software, and finally ended up using this for my blog site, because of two reasons--
a) Very flexible. I can expand my site from a simple blogging one to a more complex one with forums, wiki etc. at any time.
b) Beautifuly written and organized code, which makes it very easy to hack.
There are CMS softwares that provide (a), but for me the reason (b) is very useful, because I can hack things according to my liking very easily.