IF you remove the factory oil with a sonic cleaner and relube or wax then:
Fasted chain is the Shimano CN-7901 (Dura Ace Cahin)
SRAM PC1091R and KMCX11SL Gold are tied for 2nd 0.6 watts slower
IF you leave the leave the factory lube on; then the SRAM chain is 3.2 watts slower.
The KMC-X11SL...