Based on personal experience (3 out of 4 failed, purchased several months apart) I recommend to stay away from the hybrid drives, as I will be in the future. A limited sample I know, I could have just been unlucky, but at this point I am cutting my losses with that tech. I think with the cost of SSDs dropping, they will have a limited lifespan as a viable product in any case.
So far, I have not had an SSD fail (out of >10 purchased personally since 2009 in sizes from 75GB up to 512GB so far), though I have had one end up in a less performant state thanks to a faulty SATA cable. I have owned dozens of HDDs and had a handful fail, but nothing approaching the failure rate I have seen in hybrids so far.
As of writing this, SSDs are coming in the $0.30 to $0.40 per GB range for sizes up to 500GB.
The interesting thing here is that (as an example, plucked from Newegg today) the cost for a 250GB SSD from Samsung is currently $0.40/GB which drops to $0.35/GB for the 500GB model. At 1TB, that same drive comes in at $0.37/GB and it is on sale. This is the kind of profile we are used to seeing, however. Essentially, for the top end of any tech segment (4TB+ HDD, 1TB+ SSD at the moment) you will always pay a premium - same is true for CPU, memory, graphics, motherboards, displays etc.
This is generally how I will do my SSD shopping - pick a couple of manufacturers with good reputation (Intel, Samsung), then decide on your required level of SSD (budget, consumer, enterprise - in Samsung terms EVO, PRO, Enterprise). Once you have that, look at the cost per GB for each size offered and look for the sweet spot - that will usually be one or two rungs below the top in terms of size.
Actually this method will work for most things - CPU (use to be cost per Ghz but more murky now), RAM (cost per GB too), Graphics cards (depends, but cost per FPS in a highend game I play is how I do it), HDDs (cost per GB). There is always a sweet spot on the curve, and it will usually be a little below the bleeding edge, and frequently have sales on (so watch for them).
I see from follow up comments that you are looking at HDDs because of price, so let's see where the sweetspot lines up for those.
Edit: Updating analysis for 2.5" drives thanks to comments
Looking at 2.5" drives that would give you a little bit of a speed boost (7200 rpm) and not worrying about the interface (the PS4 is limited to SATA II) one thing that was immediately obvious is that there is not a lot of choice, here is the cost per GB of a selection of Seagate 2.5" 7200 RPM drives:
- $0.188/GB - 1TB
- $0.186/GB - 750GB
- $0.129/GB - 500GB
That 500GB model was actually cheaper than the smaller drives, so hardly a surprise that they are the default for the PS4. It's worth noting that the SSD 1TB prices are "only" 2x the 7200 RPM hard drives in the 2.5" form factor, so it's not as much of a premium as compared to 3.5" drives (see below).
Here is my original comparison, where I mistakenly profiled 3.5" drives. It's illustrative, so I will leave it here for reference:
I will pick a single brand that I have good experience with (Seagate), go for 7200 rpm drives, and not pay too much attention to other factors (warranty, cache etc.) since this is a rough estimation:
- $0.092 per GB - 500GB
- $0.049 per GB - 1TB
- $0.0375 per GB - 2TB
- $0.03 per GB - 3TB
- $0.038 per GB - 5TB
The particular model I was looking at for convenience did not have 4TB/6TB sizes listed, but you get the idea - it looks like 3TB or 4TB is your likely sweet spot from a cost per GB perspective (as an aside: about one tenth of the SSD prices above), so I would look for well reviewed, reliable drives in that range and buy with confidence (for now). Just for reference, the 8TB 7200 RPM drives are rare and are coming in at ~$0.7 per GB as of writing this answer.