Only experience I've had of WD Greens has been in my Sky HD box (original Thompson one) where I upgraded the original driver to a 1TB WD Green. The box is ropey at best, but the drive has been thoroughly used for 4 years and still going strong.
I've use WD HDDs for years (mostly the Caviar Blacks & Blues) and only ever had one actually fail, which was a 11 year old WD Black 250GB. Current machines are running a 1TB Blue in main PC as storage / games drive, and a 250GB Black as main drive in 2nd PC.
I'm using Caviar Reds (2 x 3TB) in my NAS box, but they're only a couple of months old and haven't done much work yet to speak of.
I've also got a couple of the portable USB powered 2.5" drives (one 250GB, one 320GB) and again, while they've not exactly been hammered, both seem to be good build quality and very reliable.
Overall I'm very impressed with WD drives, always have been, and given the choice would always pick them over other HDD brands.