Even on recent SATA II (more properly, SATA 3.0 Gb/s) units, the AVERAGE data throughput is often in the 80 to 100 MB/s range, because that's as fast as a mechanical hard drive can access data. It is limited by the rotational speed of the disks and the speed of moving the heads from track to track. About the fastest I've seen in any lab test is a little over 1.5 Gb/s (roughly 150 MB/s). For the same mechanical reasons, the SATA 6.0 Gb/s HDD's are NOT faster than the previous SATA 3.0 Gb/s units. This does NOT apply to SSD's - they are much faster because they don't have the mechanical limiting factors. Even then, last I looked the SSD's were achieving just over the 3.0 Gb/s rate, and have not reached the limits of the SATA 6.0 Gb/s communications subsystem. That's why that new system was designed for that speed - so it won't be a limit on the latest SSD technology. The speeds never meet the MAX speed spec for the data communication subsystem of 3.0 Gb/s.
I've never seen USB2 data transfer rates in lab tests that fast. Most ones I've seen are in the 30 to 50 MB/s range for USB2.