The best hitters I've seen swing balanced bats. It is easier to stay inside the ball and hit it up the middle and easier to work on hitting opposite field gaps. Hitters can also wait a little longer with a balanced bat before committing to swing. Additionally, the metal at the end of a balanced bat is thinner than an end loaded bat. The ball carries further as it is easier to get more backspin on the ball and there is a little more trampoline effect.
As a hitter gets older around 13 or 14 the rebound effect starts to work against them as the harder metal of something like an exogrid provides a harder hitting surface and the softer end of a balanced bat absorbs too much of the ball.
Hits are crisper with a balanced bat as contact is more consistent. If a young hitter commits with a balanced bat they have a better chance of holding their swing than with early commitment of an end loaded bat.
Eventually, hitters have to go to more end loaded bats in their early teens but young players hit well and develop better habits with balanced bats. Batspeed is a little better with a balanced bat as well as it is easier to initiate early batspeed.
I have run plenty of tests using swing speed radars and measuring distance and balanced bats are superior for young players.
Major league hitters cork bats to get better balance and control on their bats. Bat control is very important and easier with a balanced bat.