Firewire is the current speed champ, but USB 3.0 is coming and will put an end to that. If your laptop doesn't already have a USB 3.0 compatible port, you needn't concern yourself about it. (hint: it doesn't)
USB 2.0 is slower than Firewire
USB - Ethernet indicates that the drive supports both USB and network connections
USB - Firewire, again, supports both
Before you run out and get a firewire drive, make sure you have a firewire socket on your laptop.
WD has a number of nice externals out there, but I'll leave the researching which one you want to you.