Definitely crawl space over attic, you'll stay much cleaner and cooler. In the past I've used the plastic cable hangers to make things easier if your doing lots of cables (and keep them off the floor). Close any the penetrations with spray foam or duct seal and try to fix any tears in the vapor barrier on the floor. Humidity/water vapor are your enemy in these spaces, along with any furry little friends.

If you get really motivated you can even put in some lights down there with a switch a the entrance location.