If you are using a modeler pedal like a Pod, GNX4, Zoom etc... you're best going through the P.A. Or a very uncolored amp. This is because you want to here the amp model not the amp you're playing through. Also through the P.A. you can take full advantage of the stereo feature of most these pedals.

If a modeler is not your cup of tea then nothing but trying different amps will find you you're tone.