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This paper compares physically motivated Kerr coordinate parameterisations for the dominant quasinormal-mode quality factor Q220 of binary black hole ringdown, using a two-layer benchmark. Exact Kerr control layer: Coordinate efficiency is evaluated directly on the (2,2,0) spectrum from perturbation theory (qnm package). The transform (1−af)−0.50 best linearises the exact quality factor over af∈[0.30,0.95] (LOOCV RMSE 0.004), while 1/κM is best for the pure damping rate τ220/Mf, consistent with the near-extremal expectation |Im(Mfω220)| ∝ κM. NR pipeline layer: Q220 is extracted from 382 SXS binary black hole simulations and compared under a common two-parameter linear model and leave-one-out cross-validated RMSE. Surface gravity κM yields lower LOOCV RMSE than both ΩHMf and af (bootstrap 95% CIs on pairwise differences exclude zero), with the ranking stable under blocked out-of-sample validation (6/6 protocols) and leverage removal. An extraction validation shows a systematic +8.5% positive bias in the NR response relative to exact Kerr predictions, correlated with the progenitor aligned spin, indicating the NR advantage of κM reflects pipeline-level properties rather than the shape of the Kerr spectrum. Key contributions:• Two-layer benchmark: exact Kerr primary control + NR pipeline secondary benchmark• Exact Kerr ranking: (1−af)−0.50 best for Qexact; 1/κM best for τexact/Mf• NR benchmark: 382 SXS simulations, pre-registered protocol, bootstrap 95% CIs on pairwise RMSE• Extraction validation: +8.5% mean bias vs exact Kerr, correlated with progenitor spin χ1z• Blocked out-of-sample validation: κM wins 6/6 protocols including high-spin extrapolation• Weighted RMSE: ranking stable under empirical, uniform-spin, and astrophysical-prior weighting• Leverage and Cook's distance diagnostics confirm ranking robustness• Main conclusion: af and ΩHMf are clearly inferior; leading coordinate within the surface-gravity class depends on observable and benchmark layer Companion papers:• Paper A (Transformer Distillation): 10.5281/zenodo.18974716• Paper C (Bridge): 10.5281/zenodo.18977541