the best or ultimate is very subjective
I would say that terms like "best" or "ultimate" or even "wonderful" (which teajay used) are all conditional on many different factors. It is very hard to spell out those factors in a way which justifies terms of praise (best, ultimate, etc.)
However, they are not "subjective" strictly speaking any more than the word "green" is subjective. We typically agree when we see it, we differentiate it from "red", we know it’s in a different category than "smooth" or "airplane," and this level of agreement enables us to coordinate our actions.
The same kind of agreement must apply to terms like "best" or "ultimate" or they are nonsense words that make sense only in the mind of the speaker and not worth using at all. Writers and readers need to understand how those terms are being used and what justifies that use.