Thanks Dr Spook 
So here is the question ?
If you had a Playstation 4 and you wanted to upgrade the drive in the next week which would you choose if money was no object 
Money no object eh? That means I'd have to seriously consider a 1TB SSD but presently all the intel out there suggests for performance purposes a hybrid drive is a good bet but again you're restricted at 1TB in size and you said previously you wanted more space?
So, what I'll do for ya (as we're pals and all), is take a looksie and try and find my mate a nice 2TB hdd that's got a good reputation for speed and reliability. At the moment, I honestly feel - as space is your main requirement - that you should go for a 2TB drive (or thereabouts) if you're not in the habit of uninstalling games and all that carry on.
So, my questions to you first:
How much space do you really need? We'll forget about speed. I hear these PS4 games use up enormous amounts of hard drive real estate. Is that true?
How would you feel about buying another drive in future (and having to reinstall again stuff at a later date)? Right now, I'd be tempted to just click on kamelion's link to Scan and just get the 1TB Seagate hybrid drive then buy another 2TB drive or whatnot in future. That's what I would do.
Also - a note about overheating. If anyone had read my linked article/s, they'd have seen that apparently heat is not an issue with faster spinning hard drives in the PS4.
Be patient. That's my final bit of advice as you're not in danger of running out of space any time soon so it's not affecting you just yet. However, just get the Seagate drive if you like for now. Keep the old Sony provided drive of course. Or, if you're feeling adventurous, you could do some Professor Timey inspired research and buy 4 drives: that 2TB Green one (WD), the Seagate Momentous XT (1TB) @ 5400 rpm as well as the original Seagate Momentous XT (750GB version) @ 7200 rpm and a 1TB SSD that has a good reputation/spec for the PS4. Then you could put them all to the test and make some fancy graphs and talk the PlayStation community through all the pros and cons yourself. Get your stopwatch ready!