This is not a question of which is better. They fail differently, cost differently and suit different jobs — and the failure difference is the one people discover last.
Hard drives give you capacity per pound and hold data well unpowered. SSDs give you speed and shock resistance. The sensible answer for most people is both.
Nothing beats a hard drive on pounds per terabyte, which is why bulk storage, NAS units and archives are still spinning disk. They also hold data well when unpowered — a shelved drive keeps its contents for years, where an unpowered SSD can slowly lose charge over a long enough period. For backup drives that live in a drawer, that matters.
And when they do fail, they usually fail mechanically with the data still physically present, which makes recovery a realistic prospect rather than a gamble.
An SSD is several times faster for everyday work and dramatically faster for random access, which is why a machine feels transformed by one. No moving parts means no noise, less heat, lower power draw, and survival of knocks that would destroy a spinning drive — the single biggest practical advantage in a laptop that gets carried around.
For the drive you actually work from, an SSD is the better choice by a wide margin. The argument is only about what you store on the other one.
Hard drives fail gradually and audibly: bad sectors accumulate, transfers slow, and eventually something clicks. You usually get warning, and the data usually survives on the platters afterwards.
SSDs fail abruptly and silently. The commonest catastrophic fault is the controller, which gives essentially no notice — the drive works on Monday and is undetected on Tuesday. SMART reports flash wear well and controller health barely at all. Add TRIM, which genuinely erases deleted files within minutes, and an SSD is both less predictable and less forgiving.
SSD for the system and working files; hard drive for bulk storage, media libraries and backups. That combination plays to both sets of strengths and costs less than an all-flash equivalent.
Whichever you use, the backup is the part that matters, because both fail and one of them fails without warning. If a drive has already gone, recovery is from £300 +VAT for a single drive after a free 48-hour diagnostic.
Cost per terabyte, above all — nothing else comes close for bulk storage. They also hold data well unpowered, which suits archive and backup drives, and when they fail the data is usually still physically on the platters, making recovery a realistic prospect.
Moving parts that wear out and do not survive being knocked while spinning, much slower access than an SSD, and sensitivity to heat and vibration. Every hard drive has a service life and will eventually fail.
They fail less often from physical causes but far less predictably. An SSD gives almost no warning — controller failure is the commonest catastrophic fault and arrives suddenly. A hard drive usually deteriorates audibly first, which is a real advantage if you act on it.
A hard drive, generally. Cost per terabyte matters most for backup capacity, and hard drives hold data better when left unpowered for long periods. Use an SSD for the drive you work from.
A hard drive, usually. Mechanical failure leaves the data intact on the platters. On an SSD, TRIM genuinely erases deleted files within minutes, and where the flash itself has degraded there may be nothing left to read.