I have the TDK and I absolutely love it. I don't know about the Plextor package, but here's the notable things that came with the plextor drive:
An insert in the CD-case to prevent shipping damage. A pen meant to write labels on CD's. It won't leave marks through the bottom and ruin CD's like a regular pen does but its fine enough to write a lot of junk on a CD (hell, artwork if you are so inclined). Dummyproof manuals (a lot of 'em . . . there is just no way to screw up), 2 CD-R's, 1 CD-RW, A purdy box, and some other stuff I just can't remember. Overall it gave me the impression that they care compared to the scant offerings of other companies.