If we don't know what you have we can't answer for sure, but assuming you have none of the above w a perfect moveset I would say in the current meta my first priority would be either Tyranitar or Machamp as they would be most useful currently. I'd choose machamp because B&SE is probably less useful than C&DP is right now.
My 3rd choice would be the dragonite and my fourth would be the Rhydon.