If you were about to use TWO different architectural styles in your design, and one of them was modern style. What would be the other? And Why?

I wouldn't go with something too traditional with modern...
Maybe something simply solid, but still not traditional nor too modern in a Frank Illoyd Wright sort of way.

Modern Living room Furniture , paints and light units ,, IT's Entrance is Wide with three Ogee Classic arches ( middle wide arch and two narrow ) , with edges is covered with Twisted Beige hashma stone ,, these arches are hanged on Thick Twisted hashma Columns Sorry for long explanation ,,, I just Love it :)

It is not appropriate to use two different styles for the same project.