Which ones?I wouldn’t say the D15 would be undoubtedly better, there are a number of coolers that do just as well if not slightly better than D15
If a Mugen 5 or FS140 or TS140 with fan replacements can compete with the D15, why even consider the D15? Its more than 2x as expensive.What Owterspace said. While NH-D15 is one of the best it is defitively not the single 'best' cooler. It's just one of many with similar cooling ability. Cooler like Silver Arrow (all varients) Frost Spirit 140, TRUE Spirit 140 Power, Le Grand Macho, Fuma 2, PH-TC14PE, R1 Ultimate, and the list goes one.
Also keep in mind NH-D15 has 1500rpm 140mm fan while many others have 1200-1300rpm fans, and still other have 2500rpm fan/s like Silver Arrow IB-E Extreme & AM4, 1800rpm fan like Silver Arrow T8 or 38mm thick 2000rpm fan like HE01 has.