Many times have I offered this opinion and I'll say it again.
Hard disks are sold by companies that manufacture them in many different factories throughout the world.
Although the hard disk supplier companies design and plan the basic product the end product is very much dependent on the quality of materials and production used in their making.
And that, of course, will depend on the factory and to some extent it's location.
On top of that some manufacturers will supply orders for other companies which are the same disk but with a different badge.
What this means to me is that the purchase of a hard disk is very much pot luck so I'd say go for a known make, specification and price rather than listen to people's recommendations for certain makes.
Any advice any individual will give you will very likely be based on their own experience with certain makes and you will find this advice varies a great deal, probably because of the reasons I have outlined above.
Were I to use this method to recommend certain makes then in all honesty all I could recommend would be Maxtor and Hitachi drives cos those are the ONLY two makes that haven't let me down and I've been using hard disks for 14 years now. Lots of them.
By the same maxim were I to advise against purchase of one make because of my own experiences of hard disk failure then Western Digital would be the biggest rogue of hard disk manufacturers ever cos I've lots of those fail on me.
But no, I'll still buy a Western Digital disk if it suits my requirements. And their Velicoraptors are superb.
And for what it's worth - and this is not entirely logical - I favour Hitachi at the moment despite the fact they took over manufacture of IBM hard disks which had possibly the highest failure rate of hard disks ever in history.
Perverse huh? But Hitachi disks have been good for me.
So, my advice, just three things - known leading makes only, specification, price. And perhaps if it's an external disk - cosmetics.
Though it may be worth considering buying a caddy and putting your own hard disk in it yourself - this provides flexibility and usually a more robust device.
And FWIW all I've said above applies to optical drives as well, and that includes Plextor.