I think Floyd has fought the right guys at the right time. Whether that's called ducking or not is up for discussion. His best win IMO is still Corrales (close to 10 yrs ago).
Donaire is still in the prime of his career, and even as recent as the Arce fight he mentioned with Arum literally right in front of him "I've been telling my promoter for almost 2 years I want these fights (Mares, Rigo), they need to happen. I'd definitely would like the Mares fight".
I don't consider Donaire a ducker, but to pick between the two....