Which drive for Time Machine

Many choices, but I suggest giving yourself all options - your MBP has USB, FW400 and FW800 - might as well get a drive with the same choices. FWIW, Lacie has worked ok, while Wiebetech and Iomega have been very good as well.

USB2.0 may have higher on-paper specs than FW400, in my use it is slower 99% of the time.