I'm very much a fan of the numbers 6 and 12 because of their many factors. If we counted in base-12 instead of base-10, and had a metric-like unit system based on multiples of 1728 (which is "1000" in base-12), we'd get both the simple notation and arithmetic of the metric system, together with very mathematically convenient units. 10 has the factors 2 and 5. 12 has the factors 2, 3, 4 and 6. It's far more useful as a numeric base.
@tae_lesion If you read the gajillion articles on duodecimal that exist on the Internet, I'm sure you'll find one that explains how to solve those issues.