Trust me go with the Infinitys. By far a higher product (durability/material/sound) then both the Polk and Kenwood. That is hard to say too, since I have been (and kinda still am) a diehard Kenwood man.
Because that wasn't one of the choices. He probably has his reasons for putting up those brands specifically. But outside of those choices I would get MB Quart or Focal.
well lets see here im goin to have to go with the infinity's the polks do have great SQ but i think the infinity is better just my opinion but thats why id have to go with