Let’s get ready to rumble! It will be an operatic battle royale in Brooklyn this month when three competing companies face up with different performances of the Mozart classic “The Marriage of Figaro.” Rising stars LoftOpera and Opera in the Slope will slug it out against veteran heavyweight Regina Opera Company. Pound-for-pound, Regina has its opponents on the ropes, but we expect these novices to come out swinging right from the bell. Which company’s corner should you be in? Let’s go to the tape.