Note that the 3GB version of the 1060 also has 10% of its cores disabled, so it should get around 10% less performance than the full 6GB version.
Also worth considering, you should be able to find a current-generation 1660 or 1660 SUPER for close to the same price as a 1060 6GB, and those cards should be notably faster.
A 1660 can be over 30% faster than a 1060 3GB, and a 1660 SUPER more than 40% faster than a 1060 3GB, so you should consider those if the pricing isn't too much more. It might be worth paying 20% more for a card that gets 30-40% more performance...
1660 & 1660 SUPER:
https://uk.pcpartpicker.com/products/video-card/#sort=price&c=439,450
Another card worth considering at a lower price point is the 1650 SUPER. This card just launched, and might not be as widely available quite yet, but generally offers a bit better performance than the 1060 6GB, or at least around 15% more performance than the 3GB version, at about the same price or a bit lower compared to that card. Just don't mix it up with the non-SUPER 1650, which is a bit weaker than a 1060 3GB...
1650 SUPER:
https://uk.pcpartpicker.com/products/video-card/#sort=price&c=476