I personally think it sounds best by the mixing board out front. That is where the guy/gal who is mixing is standing so near them usually is pretty good. You don't want to be front and center if you actually want to hear the vocals and all that. Remember if you can not see the fronts of the speakers, you are not going to hear the treble.
Also, depends how tall you are, further back gives a bit better angle from the people in front, and the balcony is best.