Someone asked me to give my opinion on some DE's ... well, i started from here, the default install space used and memory usage:
XFCE - 12.5GB - 386MB
Gnome - 9,4GB - 700MB
KDE - 10,7GB - 420MB
LXDE - 12GB - 250MB
I think KDE is quite lightweight, despite the "fame". On my system it takes 540MB at boot sometimes reaching 620MB
(i have 3 Activities and each has it's own wallpaper, Latte Dock has for each activity a set of launchers, Conky doesn't run at startup because i don't use it, only when i want to have fun with some scripts). Yes, we can all be happy because people from this community are so awesome!!!