What would be a good percentage of germs for an anti-bacterial soap to kill?

Fellow flutherite @Laureth provided this information explaining how anti-bacterial soaps that kill 99.9% of germs are leading to hardier, more robust bacteria that are resistant to anti-bacterial soaps.

So, assuming 100% kill rate is not attainable, and 99.9% is possibly creating a larger problem, what would be a good percentage to kill off when washing? 80%? 50%? 20%?

At some point, one must wonder if we should use anything other than tap water to wash our hands.