Big wide tall cushy tires - as wide as you can fit on your bike. Adjust tire pressure to suit. Please note, that the larger the volume of tire, at the same pressure will give a smoother ride because the pressure inside the tire does not increase as much with same tire deflection due to a particular bump.

Dropping the pressure too much will result in pinch flats.

Thorn resistant tube are much more resistant to pinch flats than normal tubes, but of course add rotating mass.