XFCE all the way because of
1. very stable for last 3+years
countless dist-upgrade ( even on SID) and no issue for all xfce versions.
2. 'very customiseable for me
probably takes some 5 minutes from fresh install to adjust desktop image, add all sorts of applets ( cpu usage, cpu coretemp, cpu freq monitor, etc), change panel from original default two to one, either on top, bottom or like unity on the left
change theme, change fonts/fonts size to make everything the right size for my aged eyes....
change theme, etc
drag and drop all the usual apps' icon to panel or at time to desktop.
install my favorite apps and add icon to panel/desktop
3. may be one important thing, I have several old computers, still running quite well, some as servers, some just normal web-surfing and media playing. often with legacy graphic cards..and I know, cinnamon does not like them.
and perhaps the real issue: cinnamon ( all versions) just loved to crash on them.
and on relatively newer CPU (i3, core2quad) it likes to hangup and consume lots of ram plus heat up the CPU.
I am sensitive to running CPU with 15-20degC hotter for the same task, which is one reason I always add sensors-applet to panel for real-time checking on any linux os. running hotter also trigger noisy fans.
4. when I install from Debian, it is very light and fast.
one can appreciate the speed when running an aged computer such as a 2G P4 single core machine.
memory consumption at idling usually around 100-120M, good for low ram , old CPU.
thunar can open a network shared file in a short time and play them