Welcome to the forum! 
I hope you realize that this here is the official Manjaro support forum, not a generic GNU/Linux forum. Therefore we will not comment on any of those other distributions you’ve just listed, other than say that they are all Debian-based, while Manjaro is Arch-based and uses the Arch Linux Package Management system.
In addition to this, Manjaro is also a curated rolling-release distribution, while the ones you’ve listed are all point-release distributions. For the end-user, this is a very different thing, because rolling-release distributions never have to be reinstalled, provided that one keeps the system up-to-date and doesn’t manage to wreck one’s installation all by oneself through bad system administration.
That all said, Manjaro offers three official flavors in terms of desktop environments, none of which can genuinely be considered lightweight…:
- KDE Plasma
- GNOME
- Xfce
Of those three, Xfce might possibly the lightest, albeit that its memory footprint won’t be far behind on that of KDE Plasma.
In addition to the official editions, Manjaro also offers three community editions…:
- Cinnamon
- i3 (a tiling window manager for the X11 graphics stack)
- Sway (a tiling window manager for the Wayland graphics stack)
Lastly, Manjaro community members have also created several spins. These are alternative versions with custom package choices and/or graphical environments…:
- DeLinuxCo spins - https://delinux.co
- SbK spins - Releases
- Mabox - https://maboxlinux.org
Additional (and recommended) reading… 