23 mm tires produced better results than narrower 18 mm versions in a recent comparison of rolling resistance. The wider tire formed a curved D shape compared to the flat based U shape of the narrower one. This resulted in a smoother ride, less rolling resistance and a greater resistance to impact, pinch-type, punctures.
The size of the contact area with the road depends on the inflation pressure. If you run the same pressure in a fat and a skinny tire, the contact areas remain the same. That being the case, it is the shape of the contact area that will change, and a D shape (above) has the performance advantage.
The main difference in cornering is related more to the rubber compound than the width of the tire. But rubber compound being equal, a wider tires has a much better grip for cornering as the contact are remains curved over a greater surface during banking around tight alpine bends.
Here's another explanation I've run across in a chat room for a similar question "Why does it feel harder on the turbo trainer with a narrow tire than a wide one?" A: Might I suggest it is simple mechanics. The air pressure in a narrow tyre must be greater to resist deformation at the area in contact. A wider tyre requires less pressure. Narrow tyres must wrap themselves around the roller of the drive wheel until equilibrium has been achieved, using F=PxA, where F is Force, P is pressure and A is area.. A wider bag will give more area therefore less deformation. Go for a 23 mm bag and it will give a better ride both on the road and on the roller than a 18 mm or 20 mm bag. Of course if you can get a narrow tyre at 200+psi the equation balances OK as well, but that requires a big effort to do that. Settle for 120-130psi.
BOTTOM LINE
A 23 mm tire, kept at maximum inflation pressure is the logical choice.
Today’s clinchers are as good if not better than sew ups. The UK article rated the 23 mm Vredestein folding tire as tops. Personal anecdotes speak highly of the Open Corsa CX 23 mm. One of my readers also suggested Veloflex tires.