Fellow N.NJ here. As K2 said, they did a great job with the Altima. As a 3.6R owner, you're def going to go through more gas than an Altima and from what I can tell, the tech on the Altima is far better. As you said, it comes down to MPG's or AWD.
IMO, FWD for the most part is just fine for most consumers. I personally only buy AWD vehicles ever since we started buying Subarus. Subara AWD isn't bullet proof and it doesn't mean AWD makes you stop better in rain/ snow, BUT AWD gives me the confidence that I can get through pretty much any inclement weather without thinking about it.
So I would say go for the 3.6R, but be sure to test drive the new 4cyl.... I've heard that it drives very well especially with the updated CVT. That is a little more apples to apples going against the Altima for MPG's.