My reason: I've been using VirtualBox for running dev server environments. What happened: VM shutdowns, without any way to start them again (buttons just gray), files corrupted, interfaces lost, ....
Except for OSX VMs built using Fusion's built-in capabilities. The other VMware products don't ship the required libraries to boot them.
You have to downgrade the vmx to prep a fusion vm to be loaded into esx. Or you can download the vmware convertor app that will transfer the vm, convert the vmx, and register the vm in esx.
I use the application weekly for this task.
I meant OSX as a guest OS.
Also, VMWare VMs will work with any VMWare product so if you are working with a team that uses VMWare elsewhere its nice to have.
If you are just trying to run a Windows app or two you are probably better off with VirtualBox since its free.