Well, first of all, you should go to Storagereview.com for any questions about harddrives. Nothing against Anandtech and all of the "gurus" here, but... storagereview is THE place to go for these types of questions.
That being said- I'd go with the Hitachi.
I did lots of research on this very subject, and was torn between the Hitach T7K, WD, and Samsung Spinpoints. I ended up with the Hitachi for my RAID, and Samsungs for my "other" drives. Basically, the 16meg cache really doesn't make a difference 99% of the time. The WD is a nice drive, but overall the Hitachi T7K is a little better in various benchmarks- and has the best access time outside of the Raptor. The Spinpoint SP2004C's are very quiet, and have the fastest transfer rates of all the sataII drives, but slightly slower access times.
So, I'd suggest either the SP2004C or the Hitachi T7K series.