With USB you can transfer information up-to 480mbps, with WiFi under the best reception your max transfer rate is only 300mbps
Wired will always be faster.
Same applies to your computer if you were to plug in into your modem directly, using Ethernet gives you up-to 1 Gigabyte of transfer rate, WiFi again only 300mbps (1/3 of the Ethernet speed).
WiFi sync is more convenient, but I wouldn't say faster.