The iPhone XS model is better than XR because of the following reasons.
It has a more attractive display than the XR.
It has a lighter weight than the XR hence it's more comfortable to hold in hand.
It has a dual camera hence it can easily zoom photos. This is lacking in XR, which makes it not ideal for photo lovers.
They both come in several colors but the former comes in silver and gold colors. These are popular colors for those who love stylish and classy looks.
The plastic border around the display (bezel) for the latter is thicker than that of the former. This makes it less appealing.