I vote virtualbox,
1.)免費
2.)Network copy file快過vmware(要行NAT(get ip from vmware network) + Bridge(get ip from router)先快)
3.)行ubuntu開server (如經router port forward) 個vmware係short short地, router set左port forward都係唔得的
4.)如guest os行linux, virtualbox 個guest os tools一click就set好. 個vmware guest tools要手動set的
copy/paste over guest/main os 都唔係下下work, 如過linux os live update 之後又要重新set 過.