Comparative behavior of quantum coherence measures in noisy channels: From static bounds to ranking reversals

In this paper, we study single-qubit coherence with the central question: when and why do different measures disagree enough to reverse channel orderings? First, we compile closed-form expressions and analyze behavior on pure and mixed states across widely used quantifiers. Next, we compare noisy evolutions using two resource-theoretic measures the [Formula: see text] norm [Formula: see text] and the relative entropy of coherence [Formula: see text] — on a common basis, enabling unbiased cross-model comparison via an iso-measure protocol (fix one measure, read off the other). Finally, we delineate conditions for ranking reversal: we establish a no-reversal regime for basis-consistent unital, phase-covariant evolutions on equatorial inputs and identify mechanisms that permit reversals nonunital population bias and axis mixing that couples transverse and longitudinal components. The framework yields actionable, side-by-side rankings and clarifies when conclusions depend on the chosen quantifier.