MaboxLinux has the lightweight of OpenBox with the power of Manjaro (ArchLinux). If you know how to use Arch (or how to use the awesome Arch Wiki), Mabox is a really great choice.
Also, don't forget there is some time to custom everything ! MaboxLinux is good by default but it can be really more powerful & beautiful with custom menus / shortcuts / ...
On my laptop, I try to made something more clean for writing (with distractionless editor, more minimal theme, ....) and Mabox is really good for this usage :)
I have not tried Arch yet, and I come from the RPM world, with Opensuse being a longtime favorite. Now I prefer small distros. I will try Mabox and see.
OpenSuse is very a very great distro for "Enterprise-class" computers. When I was young, I worked in a research lab (in a unviersity). All the "experiences computers" was on Opensuse and I liked it !