I can't really comment objectively on Django CMS, as I've had no exposure to it. Too busy working on Mezzanine.
I did at one point take at look at their page model, which I imagine in both projects is the heart of the CMS. It was a relative mess compared to Mezzanine's, which has always strictly strived to keep a painstakingly clean code base and design, to make jumping in and hacking on as easy as possible.
I've also seen a lot more complaints from frustrated Django CMS users than I have with Mezzanine, many of those who have come to Mezzanine afterwards and really enjoyed it. But that is most likely a result of Django CMS being much more popular - something Mezzanine has a much harder time achieving without a generic name :-)
But please, take that comparison with a grain of salt. Go ahead and try both!