Real-world pricing of these drives and other comments...
It would be nice if you made the effort to actually gauge the real-world pricing of these drives before publishing your review.
You state the Samsung is the most expensive of these drives yet it is in realtity the cheapest, costing just £119inc at Savastore.com! In contrast the cheapest price for the Seagate is around £138inc, and likewise for the Western Digital GP. The Hitachi is still around £150inc. Thus this spins the conclusion that the Samsung is the performance monster but seriously hampered by pricing on its head, and effectively changes your review.
Also, mentioning the various warranties would have been nice.
A bit of attention to details like this would really help with your reviews as it really doesn't take much effort to get the info.