You know what bugs me? Presenting a relative with a cup that says "World's Greatest Dad" or "World's Greatest Mom" or "World's Greatest Whatever." And here's why. There are seven billion people in the world. And how many of them do any of us know personally? Less than one percent of one percent of one percent of the total. So how in the world can we know our Dad or Mom or Whatever is the "World's Greatest"? Answer - we can't.
To have a prayer, we'd need a worldwide evaluation, something that hasn't ever been attempted to my knowledge. And even if it were, what would the appropriate criteria be for this "Greatest" category? There are countless possibilities. Best dad in terms of getting his kids ready to be productive members of society? That could be good. Or maybe best dad in being supportive of his kid's dreams. Totally different from the first.
Yeah, there's not going to be any consensus, that's for sure.
Here's what I would have suggest, if I were in charge. Cups that say, in small print since it's wordy, "Best mom, as far as I'm concerned, of all those moms I'm personally aware of." Now THAT would be accurate.
Unless, of course, you really should have bought the "Fourth best mom, currently, of those moms I'm familiar with. And I'm only familiar with five." But in that case, maybe a box of bath soap would be a better option.