The repo is full of any software you might need, including proprietary (through xbps-src).
Everything just works, if it doesn’t it’s probably your fault.
It’s a rolling release distro, yet focused on stability and usabilty, so you won’t get the latest and greates, but instead builds that are known to be solid. For example the kernel, it’s not the latest, as is with Arch, but it’s maybe one or two minor versions behin. The same applies to software, they’re known to jump versions if the current build proves to be unstable.
Lightning fast boot up. It’s also the fastest distro there is, apart from the *BSDs.
Compiling and testing is a breeze thanks to xbps-src.
A lot of tools and scripts that make building templates for software not in the repo very easy.
Supports a lot of architectures. NetBSD is the only other POSIX OS that supports more architectures than Void.
There are other things, I’m sure, but these are the ones I can think of ATM.