Out of 3, which is the best:
Nvidia's Driver on the cd that came with the card
MS' driver from Windows update
Direct download from Nvidia.com
All nvidia cards are based on an Nvidia reference implementation, so there really isn't anything special about any particular card besides the fancy picture they stick on the cover.
So XFX GTX260 = BFG GTX260 = Gainward GTX260 .. they're all the same. minor differences in how they're clocked from the factory and are unlikely to have some "secret sauce" proprietary driver.
You'll want the direct Nvidia driver because that is the one that is updated most often.
Nvidia's driver that is on the cd that came with the card.
This driver is going to be the most stable and rock solid for your particular card. There is only so much performance that new drivers can really offer, and all too often can a new driver end up causing issues (not just hearsay, have dealt with 2 different cases of this recently). If you want to just install and forget about it, go with what is on the disk.
Edit: As I was saying about updated drivers causing issues. Here's a CURRENT issue where a new driver revision can cause the fan to fail on Nvidia cards, potentially causing PHYSICAL damage.
The Microsoft Update is best because
At the core they are same code made by same people. But what matters is the amount of eyeballs watching after the quality. I can guess that with installing just Microsoft drivers you can get some extra valuable pieces like resetting of some unofficial overclocking made by card manufacturers behind the scene which can help with stability.