It would be. Exit pupil diameter is what dictates the compression of light sent to your eye, a 42mm runs about 20% less light than a 50mm at the same zoom setting. If you were comparing the Nikon at 15x vs. the Vortex at 16x, you're talking about more than 25% more light passed by the Nikon, and if you were at the opposite end running 3x and 4x respectively, it's almost 60% more light. At the top end, you're talking about about 2.5mm exit pupil with the vortex, which for some people, is as small as their pupil can possible constrict, let alone when their eyes (especially their off eye) are dilated wide in low light.

A more fair test would be to run the Nikon at 15x, and the Vortex at 12.5x. That'll put both at 3.33mm exit pupil.

Nikons generally do have better resolution and better contrast than Vortex of similar price points, but that's not saying much. Nikons also tend to have much worse edge distortion than the Vortex's, or really, any other mainstream brand. Not a big deal for hunting, but it's a headache waiting to happen if you spend much time in the scope. Neither are famous for tracking or adjustment consistency, but for a hunter, both are serviceable.

If a guy buys on political history, then Nikon wouldn't be on any hunter's list. They make their money from their camera lines, not from sport optics, so their lobbyist money gets directed by dems and libs - lots of support for anti-hunting organizations. I'm not usually one to follow politics, but Nikon is one which I don't believe deserves our money. To each their own, I suppose.