Did a quick test on my 6D, M, and Mac Mini (current generation), uploading 197 photos (raw+jpg - about 5.6Gb) from a SanDisk Extreme 64Gb (45Mb/sec) SD card. Cameras are obviously USB 2.0 devices, Mac Mini has USB 3.0 ports and thunderbolt. I normally use the Mac Mini's internal SD slot when uploading since its most convenient and should be the fastest.
2:22 via internal SD slot (Memory Card Utility)
5:13 via cheap external USB 2.0 card reader plugged into USB 3.0 port (Memory Card Utility)
5:59 via USB cable from M plugged into USB 3.0 port (EOS Utility)
6:12 via USB cable from 6D plugged into USB 3.0 port (EOS Utility)
?:?? via wireless from camera to Mac (EOS Utility) - it was taking about a minute an image so I gave up rather than wait 3+ hours. I might rerun this again sometime - there was possible interference.
No surprises. I don't have a USB 3.0 card reader, but I would be surprised if it did any better than the internal SD slot. The M & 6D did well via the USB cable - Canon has a pretty good file transfer utility. Wireless performance disappoints - definitely do not use wireless if you have any other choice.