Well, there is no food, water or fuel left on the Moon. That leaves purely the equipment. There are a few candidates for interesting objects, namely:
- Power sources. Of those available, the best would probably be the RTGs, both for a source of heat and of power. These are likely intact, due to their internal heating, they probably don't change that much in temperature from night to day. They come with dangers, however, of leaking radiation. There was one each for the later 5 Apollo missions. There aren't any large solar panels.
- Fuel tanks- The best of these would be the Apollo missions, they left the descent stage, which should be pretty cool.
- Lunar Rovers: As has been mentioned, these were in poor shape, but they are still something of interest.
- Communication devices- Nothing on the Moon can talk to Earth now, I wouldn't count on anything being particularly useful.
Thus, purely on the basis of what's already there, either Apollo 12 with its Surveyor/ RTG/ Descent stage, or perhaps one of the 3 later Apollo missions, with the addition of the Rovers.
I should add that none of these compare to liquid water in terms of its usefulness, nor with the solar power potential near the South Pole. So Shackleton Crater remains the best place to land on the Moon for its resources, from Earth or otherwise.