The word you're looking for is "subjectively". There are lots of aesthetic reasons to like the metric system but realistically the best one is the one you have internalized.
You can only clearly judge two things if you have them both internalized.
I for example speak German and English and I can assure you that both these languages have their merits. German is a more precise language with more nuance and a bigger vocabulary, chaining of nouns allows for ad-hoc invention of new words which other people will quickly understand etc. English is much easier to learn, is less clunky to express everyday stuff and it lends itself to certain ways of thinking that I wouldn’t want to miss.
While these are based on subjective observations there is plenty of research that shows how language affects thinking and one could argue there are objective differences.
Are the benifits of metric prefixes, a decimal base, better interfacing with Si units etc really just subjective?
If you live in an imperial world, these benifits might diminish, but using this as an argument would be similar to saying “German is not a good language because where I live it is not spoken”
Please explain how you think Celcius is objectively better than Fahrenheit. For the layperson the only difference is that Celcius requires decimal points to distinguish between temperatures you can feel and has a simple water boiling and freezing poin
Back to the larger point: if your argument is that it's similar to comparing German and English, you've lost. Bringing it down to effectively a language barrier means it's obviously not worth any switching cost for a few minor conveniences.
Non-metric units are objectively worse.