The 99 Noir have black wood; the 99 Classics have brown wood.

The AKG K371 hug the Harman Curve, a sound signature that represents what "most people" sound good. Your mileage may vary. Pretty neutral with slightly elevated bass, but nowhere near as bassy as the Mezes. But they also don't have the bass bloat into the mids of the Mezes.

Good luck.