the comparison is hard to make in the first place, as Tails and Whonix are trying to accomplish rather different things. Tails is an amnestic system with Tor support, while Whonix is a persistent, isolated system, which torrifies the connection seperate from all the rest. Furthermore, under normal circumstances, Whonix under Windows is still isolated from the rest, thus is tracking done by Microsoft not really a big concern. Also, VBox isn't really deemed insecure, the main reason for not using it is that, it is not as secure (though it still overs a good layer of isolation) and that it doesn't really comply with some open source/GPL aspects.
Have a nice day,