gamingmaniac :
Why
people say that dual graphics cards have micro stuttering
Why are you even asking this if the other option is 3 660 Tis? Microstuttering is an AMD concern, and for the most part, not Nvidia's.
SLI becomes less worth it once you add a third GPU, and the gains from the third GPU is very minimal.
So two 770s would be the best choice, they do out perform a single 780.