Salix OS

I need a Virtual Machine and I've used Virtualbox some. I like the idea of an open source VM, so should I go with KVM or stick with the popular VMware?

I suggest that you try qemu .

After some study qemu does indeed look a better/faster VM that vmare. Is qemu better by itself? Many people say that kvm is a accelerator for qemu. I

P.S. I am not a fan of red hat & co. stuff(cough, systemd, cough), so I would prefer to use just qemu, unless kvm+qemu offers some benefit.

kvm has nothing to do with Red Hat or systemd. A quick Internet search would have leaded you to this answer:
https://wiki.qemu.org/Features/KVM

Have a good day,

Didier