If you are like me, you're probably completely confused by the plethora of identical sounding models of 4TB drives. Here's a decoder ring focusing in on warranty (reliability really), performance (mainly rotational speed) and NAS-able (various fast error protocols). The sweet spot for NAS seems to be the Seagate ST4000VN000 which I've been buying and if you are a gaming geek, the Seagate ST4000DX001 Hybrid drive.
Seagate Desktop Drives
These are relatively modest performance and they don't have various NAS features (basically all about error checking, with NAS, you want errors to bubble up immediately:
ST4000DM000 now called HDD.15 (huh?). 5900 rpm. This is a barebones desktop drive ($164 from Newegg). ST4000400. This is the retail kit version of the above.$179 from Newegg
ST4000VN000. This is the small scale (1-5 bay) NAS version, it comes with NASWorks which fine tunes error recovery. The main thing that NASWorks does is that if there is a disk error, the desktop system can take 20 seconds to recover so you need TLER (time limited error recovery). Most NAS assume after 7 seconds the entire drive has failed and starts rebuilding. Then there is additional vibration damping as lots of drives can get crazy. $190 at Newegg. ST4000VM000. 4900 rpm.$200 at Newegg
ST4000DX001. Hybrid drive so good for desktop where you get the SSD caching working for you. $217. STCL4000400. The above drive as a retail box.$240.
ST4000NC001. Their Terascale HDD (renamed Constellation CS). Expensive at $290 at Newegg, but good reviews. Bare drive. ST4000NC000. Includes the ability to instantly and securely erase the drive.$300
Western Digital
So instead of long long names with zeros, they like to use colors:
WD Green. 2-year warranty, cool, quiet and 5900 rpm slow for desktop
WD Black. 5-year warranty for performance. 7200 rpm
WD Red. 3-year warranty. With NAS features for 1-5 bays. Nice features, but Newegg users report lots of reliability issues.
WD Purple WDPurx. 3-year surveillance drives (not sure what that means. $190 optimized with TLER and different write caching for video streams at low bit rates WD Se WD4000F9YZ. 5-year. 5-=12 bay NAS for SMBs. Has RAFF vibration canceling, TLER for error recovery. These are quite a bit more expensive at$270 at Newegg, but may be worth it if they re more reliable.