I just tried both recently. Been using VirtualBox for work and X11 is super slow. With Parallels, X11 ran fine but I couldn't get OpenGL to work with Parallels Tools installed (actually nothing that used OpenGL would work).

With VMware Fusion, OpenGL worked out of the box and Extreme Tux Racer and ShaderToy ran fine.

Also, in VMware Fusion I could disable all MacOS-shortcuts (like Spotlight and switching spaces) while the VM is in full screen... With Parallels I would always switch spaces by accident because I couldn't find a way to disable everything...

Better UI, no scammy "buy our other product" buttons in the app UI, no misleading pricing. I always found Parallels to be quite shady.

Support for disk formats other than Parallels own format. VDMK and VDI and other formats are actually usable on VMWare and VirtualBox but you're out of luck with Parallels.

I am having both products and currently I prefer VMWare. One of the biggest reasons is, that all necessary drivers for Linux inside VMWare are part of the Linux distributions - e.g. CentOS and Fedora run without extra drivers installed.

Parallels brings their own drivers to install, which means not every Linux version is supported, the last time I tried it was lacking drivers for the newer kernels, this seems to have improved somewhat.

VMWare requires a few more clicks to configure with the upside that you have a clear configuration process so little magic is happening in the background - Parallels seems to automatically mount your drives in the VM which often is not what I want it to do.

Also, VMWare supports platforms beyond the Mac, so if you have a mixed environment, you can even move VMs between e.g. Windows and Mac machines.

Well Parallels is owned by Corel now but Fusion isn't.

Free account for personal use?