The assertion that would be easiest to objectively verify is: "The trees are in the ideal spot to create shade."
This can be determined based on the position of the trees relative to the house and the sun's path, allowing for an assessment of whether they will provide shade in the afternoon. The other assertions about the beauty of the lawn and the yard being the envy of the neighborhood are subjective and rely on personal opinions and future circumstances, making them harder to objectively verify.