In respect to this, is a 1060 3gb enough?
TBH, a 3GB video card is not really enough for a lot of newer games, even at 1080p. Plus, the 6GB model is barely more expensive and really doesn't hurt to get the one with the higher VRAM capacity. Perhaps waiting a tiny bit longer for the release of nVidia's next GPU's would be a slightly better option.
Secondly, is there a big difference between GTX 1060 3gb and 6gb? the spec wise the 3gb has half the Vram and slightly fewer cores. the 1060 6gb is 7% better for 15% higher a price. but in games its a 17% difference. for gaming the 6gb is a must as well as most games will go over 6GB of Vram anyway at high to max settings.
Furthermore, is 3gb VRAM enough for 1080p?
1060 3GB --> 1060 6GB). Because you are playing at 1080p, a lot of the games you will play will not exceed 6GB of memory used (total). Hence, it is optimal to have a good memory setup (fast speeds and low CAS latency) that simulates VRAM if you are to have a 3GB GPU.
Is a 1060 still good in 2019?
Yes. I'm using a 6GB one as we speak and it's really overkill even when you max settings out for most games. I have a 1060 6GB running two 27" 1080p monitors and am still able to high/max game settings with good performance. If you're operating on a budget I think it's still a fantastic card that is totally capable.