More elk , easier access if you don't know either area 17 will be a bit easier to find elk , just go to the mtn , where as all of 13 is elk country but they are scattered . 13 is a good unit , but if you can scout it or hire a quality guide , other wise be prepaired to to lots of miles for little and possibly no elk siting , where as 17 has just a certain area , the San Mateos , elk on both sides , its good elk unit.