I came across this seven years old reddit thread[1] which generally advocates VMWare and proclaims Virtualbox as "sluggish". But that was seven years ago, are the state of things the same these days? What would you recommend to a beginner who is still learning virtualization?
[1] https://www.reddit.com/r/windows/comments/19appt/virtualbox_vs_vmware/
I'd recommend just sticking with VirtualBox unless VMware has some feature(s) you need and/or you have the extra money to blow.
You can even start with VirtualBox and move to VMware later if you find a reason to. You can easily convert any existing VMs back and forth, etc.
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(I've got a full vSphere cluster here in my home lab and VMware Workstation on my workstation and primary laptop. I've decided that I won't be giving VMware any more money, though.)