The "best type" is the one she can hit with! ?That's not always an easy thing to figure out and unfortunately you usually don't get to try out a bat before you buy it. ?
My opinions....
Longer bat generates more centrifugal force, but loses bat speed and control. ?Swing easier, good distance...if you hit it on the "sweet spot".
Shorter bat generates more bat speed, better contol (to a point...). ?With today's composites and high tech materials, most bats will generate a great deal of force if hit squarely.
Lighter bat should allow more bat speed (to a point...), shorter distance hit IF swung at the same bat speed as a bat with the same length but heavier weight. ?Bat speed is the key there...
Heavier bat...ONLY if you don't lose bat speed.
End loaded bats....I personally think these bats help correct a lot of kids' problems like "casting" because the weight distribution forces a better hand position. ?However they are also harder for physically weaker players to swing.
In general, bat speed is THE factor to be most concerned with. ?I would never sacrifice bat speed for anything.
So...you can kind of go from there. ?If your daugther hits the ball a long way, but doesn't make much contact, maybe going to a shorter bat would be the thing. ?If she is a great contact hitter, but never hits it past an outfielder, maybe a longer bat would help, or an end loaded bat of the same weight.