Ref Newegg ( Nr = Nr respondants, * = Stars)
Samsung F3 Nr. 690 4/5 * - 83%, 1/2 * 12%
WD Blk Sata 3 Nr. 2589 4/5 * - 86 %, 1/2 * 10 %
WD Blk Sata 6 Nr. 359 4/5 * - 80 %, 1/2 * 12 %
Seagate -12 Nr. 859 4/5 * 65%, 1/2 * 30 % OUCH!
Based on this I would get the F3, as The data only shows a marginal increase in Possible quality. Noe:t neither has been around long enough to really say one over the other (ie 5 yrs) Seagate got into big trouble with it's -11, the -12 is better, but I would say still 3rd rate.
PS I bought a WD Blk 1 TB Sata 6 drive on the spur of the moment - GIVE ME Back the cost diff between it and the Samsung F3 (SATA II) and I would do it in a heart beat.
To the question reliability of single 500G platter drive to 2 x 500G platter drive, same make/model (except for size) - Yes the single platter will be more reliable.
Does that mean if you buy two 500 gig single platter drives and I buy a dual platter drive will yours last longer than mine - Heck, I might be Irish and you got up on the wronge side of the bed the day you bought yours.
Added:
In the past 2 years, I have bought 1 Seagate 1 TB drive (took a chance), One WD blk sata 6 1 TB drive (my Bad), and about 4 640 gig WD black (Love the WD bl 640's in raid0)
I also you to swear by seagate, untill the -11s came out.