The 1060 3GB is far better. If you need more than 3GB of VRAM, it would still be better than the 1050ti as anything that requires that much VRAM will be too much for the 1050ti to run quickly, where as the 1060 will start using system RAM and still be the faster of the two.
Of course, the ideal card is the 1060 6GB, but I'm sure you've got a budget to work to.