Best high school BOY's player in person (excluding Jordan Brand games) was Norwalk's Calvin Murphy, who is now in the Hall of Fame. He was the shortest, fastest, and best-shooting player in the NBA for years. If he had played in the 3-point era, he would have been even better. Murph's range was "in the gym." He also easily dunked, at 5'9". He was also a world class baton twirler--hand-eye coordination was next level.
In terms of GIRL's high school players in person, I'd have to say Azzi. I've seen her 9 times, including in the D.C. City Championship game against Visitation. She still holds the arena scoring record where the Mystics play.
Other stellar players I've seen in person, excluding AA (WBCA and Jordan Brand) games, include Kaleena, Aubrey, and Saylor. I also saw Ashley Owusu, Mimi Collins, Mir McLean, and De'Janae Boykin.
The best BOY's player on TV was a kid named Alcindor many years ago. NYC showed the game of the week, and Power Memorial was included often. I'd rank him above LeBron.
The best GIRL's player in video was Maya Moore. She did whatever was necessary to win and was a couple of levels above the competition. Others who stood out were Moriah Jefferson, Paige, and Azzi.