VirtualBox supports USB 1-3, it has immutable disks built-in, it supports VMDK/VDI/HDD, it lets you drag-and-drop, it supports like a gazillion different controller formats, it allows host I/O caching, and like I already said it can be just plain faster... just a non-exhaustive list off the top of my head. Are you genuinely unaware of its features and strengths...?

Port forwarding and shared folders. Hyper-V has neither, and it's a pain to migrate, and also there's a perf impact.