I do agree the 1999 team likely wins the NC. That team was the last roster of Osborne recruits primarily in the 2-deep and coming off the mid-90s dominance.
I don't think the 2001 team would have made it to the final in a playoff, and might have exited relatively early. The game prior to the NC they got demolished by an above-average CU team. There was also a very good Texas team that year that was probably the 2nd or 3rd best team in the country that was upset in the B12 championship. Oregon was also good that year and soundly beat CU in the Fiesta Bowl.
The 2000 team was actually better than the 2001 team. Their only losses were to the eventual champion Oklahoma and a KSU team that only lost to Oklahoma and soundly beat Tennessee in the bowl game.