It's really up to you what you want. I have a couple WD portables and I like them. People like Lacie ... it just depends on what you want. You could even buy a 2.5" drive and enclosure.
IF you have a 2011 USB 3.0 doesn't help. I have a late 2011 15" pro and picked up the WD studio portable harddrive. It has a firewire connection. I'd recommend a portable with firewire since you don't have USB 3.0.