Infinity G35x 2007 or Audi A4 Quattro 2007

Hey everyone I have finally managed to get closer to my car buying. I have finally managed to get a loan approved from a credit union and I am ready to buy a used car. But I am confused about these two cars now. Whether should I buy infiniti G35x sedan 2007 model that a used car in my area is coming for 23000$ with 30k miles or should I buy Audi 2007 A4 sedan quattro for 20000$ with 35k miles.
In a car what I am looking is the car that survive well in winters and I think these both work well in winters. Another thing is ride quality and more important the overall look and the interior of the car. Also the maintainence cost is something I dont know anything about and will like your feedback on.

So based on this what would you people prefer ????? is it worthwhile spending more on infiniti.