Adding this:
I have no way of knowing the accuracy of this article but there are rumors that Apple will adopt Light Peak when it is ready and I think that will probably kill firewire. You can tell Apple wants to kill it as they continue to diminish it’s importance on their new machines despite the fact that to a lot of mac users USB is a total afterthought.
http://www.insanelymac.com/lighting-a-macbook-pro-with-light-peak/
I would still recommend FW for the best day to day use today- but this article does kind of have me leaning towards USB 3 for something that will be supported in the future (since you can’t very well buy a lightpeak drive and esata will really limit your choices)
Here’s an idea- if it’s a big and expensive drive- try to get something that is meant to be or can be easily removed from the enclosure. That way if you ever have to change it- it won’t be so hard. The OWC drives are meant to removed from the enclosure- Lacie’s are a pain.
By the way- that article also talks about killing the optical drive, since Apple did it to the floppy disk, I see no reason why they wouldn’t do it to the optical drive. That is coming too, sooner or later.