I’ll add idle usage. VirtualBox shaves one-two hours off my MBP’s battery while Fusion leaves it untouched.

Vbox graphics performance also left much to be desired: e.g dragging a terminal window around was slow, produced insane tearing and huge performance impact, and no amount of tuning would help; I’m not even talking about 3D stuff, this is just some plain X lightweight WM without a compositor. No such issue on Fusion, where I just imported the same VM.