I found that using the Ethernet ports on my 1DX series bodies is the most convenient way for me to transfer images to my PC for processing and the Mark III is particularly fast with its newer interface package, the Mark II with its gigabit capability was an improvement over the original 1DX but the current model really flies. The ethernet port connector built into these bodies is simple, fast, and reliable and avoids constantly removing/inserting the expensive memory cards or using the less robust USB connector.
However, I was reminded after I bought the 1DX III that although the setup wizard built into the camera works fine for setting up the initial ethernet connection, it leaves the IP address set to automatically find an address each time the camera is connected. This works but it may take a couple of minutes each time the camera is connected for your computer and camera to establish the LAN connection. However if you set the IP address and subnet mask manually and lock those parameters during setup, then the camera will complete the connection within a few seconds of enabling its LAN adapter each time you connect it to your computer. The easy way to do this when setting up a new ethernet equipped Canon camera is to let its setup wizard choose an IP address and subnet mask and then write down these settings and choose manual LAN setup in the camera menu in order to enter them as fixed permanent settings. Using this method, the camera will select a usable address that isn't in conflict with anything else on your network and you can save those as permanent settings rather than waiting for it to go through a complete check and setup each time you connect.