The differences between FE and AIB cards, in general, include:
Better GPU cooling / lower temps
More performance
Better PCB componentry including chokes, caps etc
Less noise
More features (LEDs, LED controls, independent fan control, fan shutoff, extra software)
No throttling (applies to 1070 / 1080 ... 1060 too low power to throttle)
Additional VRM / Memory cooling
As for cost, right now the on newegg, the MSI 3 GB 1060 Gaming X offering is $229 with a $40 free game ... the lowest cost MSI 1060 is $223 and no free game .... for $6, getting the Gaming X is the proverbial "no brainer" even if you consider the free game worthless. At 6 GB, it's a $13 difference, again with the free game ... Again, even without the free game, i don't see a value to the cost savings.
While the EVGA SC series has a better cooler, historically it hasn't had any of the other PCB improvements that the other AIB cards have.