It's interesting that this question still hasn't really been answered, but here are my updated thoughts. First, Cinnamon is leading in the poll that Clem opened. Second, in maya's package list, the mate package is mint-meta-mate, whereas there is both a mint-meta-cinnamon and a mint-meta-cinnamon-dvd, which could mean that cinnamon is default and they're doing both a dvd and a cd version of it, or it could just mean that not all of the packages have been uploaded yet. Third, Cinnamon will support both 2d and 3d graphics in Mint 13, which negates the argument that only people with 3d acceleration can use Cinnamon. Fourth, mdm is more gnome 2-ish (and therefore mate-ish), so, if it's used in the main edition, it would probably go better with MATE than with Cinnamon. Finally, there's a mint-artwork-cinnamon package, which could be interesting if it's a theme or something in it. Also, on a separate note, there's a mint-info-xfce package, which could elude to an ubuntu based xfce version (there wasn't a mint-info-xfce package for lisa or katya). There also isn't a mint-info-lxde package or a mint-info-fluxbox package, but my guess is that these packages haven't been uploaded yet (although there might not be a mint-info-fluxbox because there might not be a fluxbox edition).
Dell XPS 15 l502x - Debian Testing 64-bit NetInst Xfce, SolydX 64-bit Debian Testing, SolydK 64-bit SolydXK Testing
Old Gateway Pentium 4 Desktop - Arch Linux 64-bit Xfce and SolydX 32-bit Sid