Sadly, BD can do nothing when facing malware that uses DirctSyscall, e.g., #Magniber. Also, DiskWriter can bypass BitDefender's Advanced Threat Defense easily, while WV can block both of them.
What's more, with Firewall and HIPS, WV is still free (at least for now), and much more lightweight.
So, though BD is good enough, I like WV better.