Corey. The parameters of this discussion are very vague. I mean, who is the best ever HS combo football/baseball of all time? Does this mean his play only in high school? Is it supposed to include what he eventually went on to? This is why we have answers that are all over the board. And this is why questions like this need to be specific.
So, if we are first talking about a guy from anywhere in the U.S OK. And if we are also talking about what the guy went on to accomplish then it has to be either Deion Sanders or Bo Jackson. The winner between the two might be Sanders because he is in the Pro Football Hall of Fame. We all know Jackson's careers in football and baseball were cut short so we don't know where he would have ended up. But, I would definitely give Jackson the edge in baseball. Jackson only played parts of four NFL football seasons. He appeared in 38 games and started 23 but rushed for over 2,700 yards and averaged 5.4 yards per carry. It would have been very interesting to see what would have happened if he had played both sports till age 35 or older. He was only 28 when he played his last football game and in reality, he wasn't nearly as effective in baseball after the hip injury at age 28.