If you make that number round, others become not-round.

I read [0] that the meter was defined as 1 / 10,000,000th of the distance from the equator to the (north?) pole. The measurement on which that was based was wrong and the actual distance is 10,001,966 meters. If you make that distance round, then the speed of light will almost certainly not be round (now that would be a coincidence!).

But also 1 cm^3 = 1 ml. Perhaps the ml was based on the cm^3. That's practical.

Making a round number for the speed of light or for the distance from equator to pole is practical only for geographers or physicists. What would be most practical to ordinary people as the basis for a meter? A body part (is there a particularly standard body part, with minimal correlation with body size/mass)?

[0] I haven't seen an especially reliable source