Fastest way to migrate data from Late 2016 13" MacBook Pro to 2009 Mac Pro I'd like to use Migration Assistant to migrate data from a Late 2016 13" MacBook Pro to a 2009 Mac Pro. The only connection options I see possibly working are gigabit ethernet or USB.

I'm not sure if Migration Assistant will even use USB to connect two Macs. Even if it did, I'm at the mercy of the slower USB 2.0 port on the Mac Pro.

Is it possible to transfer data using USB and if so, is USB faster or is it faster to use gigabit Ethernet?
You have three options to connect two Mac's together to transfer settings via Migration Assistant:


Ethernet
Firewire
Thunderbolt


There's no option to connect via USB.  Academically speaking, connecting via USB would be your slowest connection because it's only 480Mb/s (USB 2.0) versus Ethernet at 1Gb/s or Firewire 800 at 800Mb/s.  Thunderbolt isn't available on a 2009 Mac Pro

The easiest thing to do is to get a USBC to Ethernet Adapter and connect via the onboard Ethernet on the Mac Pro.  I recommend this over the Firewire for three reasons:


It's faster than Firewire
You probably already own a Ethernet cable; you would have to purchase a Firewire cable specifically for this
You are more likely to need the Ethernet adapter than you will a Thunderbolt to Firewire adapter