I personally would choose Dead Rising over N3. Just from the bit I've played of both, Dead Rising looks to potentially be the more enjoyable. I read/watched the reviews on 1up, and both said that it's obviously flawed but incredibly fun.
Plus the voice acting seems to be excellent, compared to the bit I heard in N3.

Check here for 'everything' you can do in the Dead Rising Demo
http://www.joystiq.com/2006/08/06/ho...d-rising-demo/