Did you mean fluorescence quenching by resonance energy transfer? If you want to find the energy transfer efficiency the donor acceptor ratio should be 1:1. But for quenching study the donor dye concentration could be anything as long as the fluorescence signal is reasonable.
Since you are trying to compare different dyes, you probably want to avoid the Inner Filter Effect. To do this you should keep your absorbance (at the wavelength of excitation) below 0.1, whether you're using steady-state or time-resolved fluorescence.
This means your dye concentration could vary significantly if their respective extinction coefficients differ significantly. Typically that isn't a problem though.