1. They are both great products. The better product depends on who ones which.
2. The sound, depends again on you. One who likes the Infinity will prefer it and those who like Polk will do the same. Take a listen and decide for yourself.
My opinion is that generally Polk's speakers are more tame and accurate, BUT the Infinity's have a more bright mid/ high end and more exciting bass. It all depends on the kind of music you listen to though...
