I would say "neither." I have had both the D2X and D2Xs for short periods of time and I would suggest that for about the same price or perhaps a few dollars more that you look at the D7000 since obtaining high resolution is your primary goal. I would go even farther and suggest the D3200 since it has the second highest rated sensor of any DX camera on the market, however, unless you have all AF-S lenses, the D3200 won't let you autofocus with the older lenses.
In addition to higher resolution, you will also get higher ISO capabilities with either of those two cameras. Anything over ISO 800 on the D2X or S will not be acceptable in a large print. Even 400 is pushing it.
So, unless you have to have a pro-built body, you are probably best off to compromise and purchase today's best technology.