Relative to its main lobes at 40 degrees, an inverted v has about 8 DB less radiation "straight up" which in theory would also make it a poor NVIS antenna. It is however better than a low dipole, in this respect, having about 4 DB more radiation in the vertical direction. Barring local terrain issues, the 1/4 wave vertical is usually going to be a better DX antenna, as its lobe elevation angle is much lower than a dipole, and has the added benefit of being omnidirectional.
Your mileage may vary, but that's what I've found. I also like my verticals because they are quite portable, which is great for "field day" use.
+-RH