Get the WD Black will be more efficient since you already have an SSD. The velociraptor would be a good addition! You'll put your OS on your SSD I guess, then games on your velociraptor. If the hybrid learns which to cache, it would also be faster than the WD Black. If you got the budget, then why not.
Oh yea it's you again, the 780 sli, build for a rich friend. Go with the velociraptor since he's got so much cash. haha