Nvidia GPUs are normally costlier than AMD with the same features as they're more energy efficient, generally quieter and cooler. They have many features like ShadowPlay, Phsyx, G-Sync. Moreover, most 3D modelling softwares are inclined to CUDA cores.
Performance wise, both are really head to head, with one racing other out in one competition or the other. Its about the efficieny, quietness, the extra features and temps which make Nvidia costlier.
If you want solid performance at a very reasonable price point, go with AMD, if you've enough budget to get the Nvidia with the same performance, get it just for the sake of above mentioned benefits.