Well, an SSD would be much faster because Seek times are near 0 ms, & seek times take up about half the time or more of the transfer. :)
My 2011 iMac Sata 3 6 Gb/s...
Intel 6 Series Chipset:
Vendor: Intel
Product: 6 Series Chipset
Link Speed: 6 Gigabit
Negotiated Link Speed: 6 Gigabit
Physical Interconnect: SATA
Description: AHCI Version 1.30 Supported
ST2000DM008-2FR102:
Capacity: 2 TB (2,000,398,934,016 bytes)
Model: ST2000DM008-2FR102
Revision: 1
Serial Number: ZFL1YMVJ
Native Command Queuing: Yes
Queue Depth: 32
Removable Media: No
Detachable Drive: No
BSD Name: disk0
Rotational Rate: 7200
Medium Type: Rotational
Partition Map Type: GPT (GUID Partition Table)
S.M.A.R.T. status: Verified
In the olden days I did have some info on Negotiated speeds, even OWC 6 Gb/s SSDS cant run on some Macs @ 3Gb/s because of the handshaking, they run @ 1.5 Gb/s, 0the SATA2 3 Gb/s SSDs will negotiate 3 Gb/s, same problem on Old G5 Power Macs some HDDs could not/would not do the 3 Gb/s speed, only 6 which the G5 could not do or 1.5 Gb/s though supposedly both could do 3 Gb/s if just sit down & talk about what they had in common.