Jejudo, South Korea
If you believe in the time/devotion argument (you don't have to) then it follows that people who read more poetry 'should' no what a 'better' poem is. This is still not an objective opinion, just a, well, how about more informed opinion?
Does this matter to what you, personally, like and dislike? Only, and I mean only, if you respect that person's opinion. If you don't it doesn't matter (and you can still respect the person, just not that particular opinion). If you do respect the person who says, he or she is a better poet (or a better stylist, or a better rhymer or whatever), ask why he or she thinks so?
The answer will either be persuasive or not depending on how both of you see the world around you, want a certain type of poetry, and, of course, how that explanation was phrased in a language the two of you understand. Actually, now that I think about it, there are other factors like mood and experience involved as well (and certainly many more).
So what is all this mess saying: Anytime someone says a certain poet is the best at anything: they mean, I like that poet better than all others either for a general feeling, a consistency, or for some specific aspect of what he or she does. It's up to you to agree or disagree (disagreeing's the fun part for me).
Get rid of objectivity. It never works. Listen to whom you respect. But never take anything at someone's word. Have fun.
Did I come full circle yet?
PS Wondering what I'll have to retract tomorrow.