Keep the 2000. It's starting to appear to be the most trouble free version. (The 2K red is destined to be the classic.
)
I think the new lights and bulge make the new Xterra look like Herbie the Love Bug. Also Nissan stopped making them out of Durasteel so we'll see how the new ones fare with rust. The floor e-brake makes offroading pretty much impossible with a standard transmission.
Also I wouldn't touch a S/C version with gas prices going up again and a war on the horizon just to have some pickup over 4k.