Mid balance rackets are neutral and offer a good amount of power and control.
Head heavy rackets are normally found on lightweight rackets, they give more power than mid balanced rackets.
HEAD SIZE:
Larger head rackets give nore power and are also more forgiving for shots that don't hit the sweet spot.
Smaller head size rackets tend to give more control but have a smaller sweet spot meaning power can be sacrificed.
STRINGS:
Tighter racket strings give more control, looser racket strings give more power.