Well, when the GTX 1060 6GB was released, Nvidia said it would provide "GTX 980-like performance". I suppose that was a fairly agreeable statement, although the GTX 980 could beat it at times especially when overclocked.
An RX 580 8GB could get you pretty close to that for $160. Heck, the new GTX 1650 Super is supposed to be a better deal than the RX 580 8GB at the same price. It was outperforming the RX 580 in some games on the professional benchmarks on YouTube. It only has 4GB vram, but it's GDDR6.
You could ensure you clear the performance hurdle by going with a GTX 1660 Super or Ti, which both have GDDR6. The GTX 1660 non-Super non-Ti has GDDR5. Still not a bad card though.