That depends on your needs.
Typo3 is very flexible and a real enterprise class CMS system with many modules. It is not so easy to manage and setup and as developer / administartor you will have to learn Typoscript, the Typo3 definition language.
Drupal is more a partal system like the phpnuke systems. e.g. Howtoforge is absed on Drupal.
Mambo / Joomla is somewhat in the middle between typo3 and drupal. Its Easier to manaage the typo3 bu has not the flexibility.
I know there was just a security problem in mamabo, but i do not know the security trackback of this project in general.
The above is all my personal experience and opinion, so feel free to post your experiences with these cms systems.