I been happy with my Hitachi 7K1000, its not silent, and i would say its not super quiet either, but in my case it doesnt get a lot of heavy use, as my programs are on my SSDs, now when i watch movies, search for files or even encode on it, i cant hear it. But i did test it outside before installing it and it had some vibrations and there was seeking noise, but not noticeable in my case.
I also bought a couple of Hitachi 5k1500 recently as i wanted to upgrade my download station to have more room to store, and i can tell you very similar noise to the 7k1000 from what i could tell subjectively. Neither is ultra quiet, but neither is a noise monster.
I did try a WD Scorpio black 750gb, and it was decent, but i could hear it more than my 7k1000, again all subjective, no real SPL.
So if you are seeking for a 1tb 2.5 mechanical 7200rpm hdd is to go with 7k1000. The one i bought was HGST Travelstar 2.5-Inch 1TB 7200RPM SATA 6GB/s 32MB Cache Internal Hard Drive
, and the box says 7k1000 (bought it from amazon but from 3rd party seller), seems like there are two skus, there is also the HGST Travelstar 7K1000 2.5-Inch 1TB 7200 RPM SATA III 32MB Cache Internal Hard Drive 0J22423
, this one i have not tested nor own, so i cant say how it is, but has good user reviews, i kinda think one is retail and the other is OEM, but i really never bother checking this, as when i bought it there was no 2 skus available, just the one i bought.