It's an old school 1TB HDD, because I really need the storage. The drive is full of VMs of every version of Windows for cross platform testing - I actually use my Mac to mostly write Windows software!

Good point though, maybe I'll be happier if I just fork out for a 2TB SSD. But at the time Apple wanted $800 for a 1TB SSD and I wasn't prepared to pay Apple's inflated prices.