Out of the 2 I would go with hard drive.
DVD will only record for 60mins and the dvd's MUST be finalized before they will play so you must be very careful.
If you get a hard drive camcorder find out what format it saves in and make sure your computer supports that format or you will be having to convert it to edit it/burn it to dvd which takes a LOT more time.
I really still prefer the mini dv camcorders, probably for another year or so as there are still some bugs with the hard drive ones.