Heres an interesting link from Google. TrendsCMS Maybe what we see as functionality for comparison, heres my 2 cents worth. Go for popularity: Typo3 Vs Mambo Vs Joomla Vs WordPress Vs Drupal.
Most likely there will be more development in that CMS and hence more people heard of it and you have better maintained systems. Its all media and hype if you are looking at CMSes and at the end of the day, its companies who choose to pay for popular upcoming technologies, including Social Networking, Zend Frameworks. etc.
My personal fav, if you are looking in to CMSes, For medium to large developments, do Drupal, for quick and simple developments, go for WordPress. If you are more for the development try Zend Framework.
CMSes are good quick front ends that are properly maintained. And for all the custom scripts, use a framework to deliver killer add on apps. That I would say fall into the category of KISS with blazing development speed, delivery and security.
I say that, but at the end of the day, go for one that you feel good with. But if you are stuck for ideas, try my described method, and then verify yourself for the best.