Benjamin's pro-death penalty position and focus on increasing resources for law enforcement make him attractive to more conservative voters, observers say.
But McChrystal, whose appointment is subject to Senate confirmation, came under scrutiny following the 2004 friendly fire death of Pat Tillman, who gave up a pro football career to serve in the Army, in Afghanistan.
But the charges against him (now dropped) for an alleged involvement in a murder at an Atlanta nightclub in 2000, where two men were stabbed to death, continues to affect public opinion of the perennial Pro Bowler.