What carries a ball out of the park is backspin. The focus should be on creating a swing that makes the baseball consistently leave the bat with backspin. That swing will be different for every player and the optimum angle that the ball leaves the bat will also be different for every player. The goal of every hitter should be to have a good bat path and keep the barrel in the hitting zone as long as possible. Ideally the plane of the swing should match the path of the incoming pitch - which would make it SLIGHTLY uphill. Anything more than that is self-defeating as the bat gets out of the hitting zone prematurely. Swings that are too uphill don't produce more home runs unless you are a big leaguer like Joey Gallo (and even he has flattened his swing out somewhat). For the vast majority of amateur ballplayers an uphill swing results in pop ups, fly outs, strike outs, topped balls, and rollover ground outs. Some of the most accomplished hitters (and hitting instructors) I know think all this focus on launch angle & exit velocity is nonsense. Kids are working on developing swings that produce a number instead of a swing that will allow them to be successful against good pitching.