Question

Why is aromatic effect is more stable than resonance effect or mesomeric effect?

Answer 1

It is subject to fewer perturbations and lower transition energies.

Explanation:

Resonance and mesomeric effects both occur with major electron location changes. While the net effect is a stability, and is often useful in reaction mechanisms, it exists in a constant state of change, and thus more energetic or less "stable".

The aromatic effect may look similar from a macro-view, but the delocalization of electrons into a molecular orbital that is not "switching" in the same sense as other resonance structures in linear molecules makes it a lower-energy state, and thus more stable than the other two types of electron sharing.