I have no clue who's who at the AD level.
My $0.02: Hire someone at the lower level that's run a full athletic department (football + basketball + all other non revenue sports). No more Mike Bobinski type ADs who didn't have to operate a full athletic program. Someone who's made hires for football and basketball head coaches. Has a proven record of hiring successful coaches at those positions. Is good at fundraising among big AND small donors. Has shown creativity with generating revenue outside of traditional revenue sources (media contracts, donors, ticket sales, etc.). Has a big vision, thinks outside of the box, and has shown a track record of how to implement those visions and ideas.
Why from a lower level? Because those ADs have dealt with the same constraints GT usually has, but at GT it will be on a bigger scale. GT will have more resources, so you hope to get a exponential affect from that AD's experience combined with GT's resources.
Assistant ADs from power programs (see: DRad) are fine, but I'd like to see a track record of heavy involvement with coaches and fundraising. My preference would still be an AD at the lower level with a proven track record.