Before making a decision you could consider reading
this.
As ReapeX7 said, nouveau (though not developed by NVIDIA) somehow replaces nv. Nouveau has its limitations regarding hardware acceleration and power management, but nv is probably no better.
Me, I recently switched from nouveau to a proprietary NVIDIA driver (aka the blob), mainly to help avoid overheating of my old but faithful laptop as I don't care for hardware acceleration. I had to reinstall mesa afterwards to get back some library, no big deal.
If all else fails you can also fall back to the generic vesa driver or even fbdev but then, forget the bells and whistles (and in the latter case you'll need an xorg.conf file IIRC).