In his thoughtful retrospective, Joe Ryan, the long-time General Counsel of Marriott Corporation, proffers sage advice. In Acc Docket, Vol. 24, Nov./Dec. 2007 at 98, Ryan puts forward the view that a general counsel is stronger whose background is transactional rather than litigation. That makes sense to me, because litigation is the unusual circumstance, not what advances the cause of the business generally, whereas contracts and acquisitions and financings promote the ends of the business.
Exceptions to this general rule might be in industries where intellectual property dominates, in which cases an IP lawyer might ascend to the top, or in companies subject to intense regulatory approval, which might give the nod to a lawyer with background in the appropriate regulatory arena.