For longevity...I say go with NXT. Here's an example, followed by details:
Now for the details.
These pictures were taken 3 weeks ago. NXT wax was applied in October of last year, 10,000 miles were put on the car since then, daily-driven, on Ohio winter roads (salt, slush, and just about any other stuff you can think of). There are a total of 105,000 miles on the car. These results are after NOTHING but a hand wash with Meguiars deep crystal car wash and using a microfiber towel to dry....nothing else. I hadn't clayed or anything yet. To give you an idea of the grime that was on there, there's this pic from my brake install:
Not the greatest pic...but it gives you the idea of how grimy it can get....I spray it once a week in the winter...but it doesn't help much on these roads.
I gotta say...I've never seen the car look better after a long, cold winter and just a hand wash :glasses2: