I have a 2012 with the NA 3.5L and have no complaints about the responsivness of the engine at all. In 2012 they only offered the 4cyl Ecoboost which did not impress. I did not mind that because I really could not justify the cost of the Ecoboost in my mind anyway. Gas mileage is rated at 18/25. I have never hit 25 on the highway but do an average of 20 with mostly around town driving.
It amazes me how sure footed it is in a tight corner. There is almost no lean and the standard Michelins are really sticky.
No matter which engine you go with I hope you enjoy driving it as much as I do mine.