A helpful answer might be that we see sunsets and mountains and so on as beautiful because they are beautiful. The reason I say that this answer is helpful is twofold. It moves the question away from the bias of a model in which (a) there is no beauty in nature, but (b) we project it onto nature, which together raise the question © 'Why these projections and not others?' That is all built into the question. The second helpful thing, as I see it, about the answer that I have suggested is that it puts the issue squarely on top of the traditional question what beauty is.
Suppose I say that Rembrandt's "Night Watch" is insipid, because it is too big (about 350 × 450 cms.) and its particular blocklike use of chiaroscuro makes it naive and primitive. I have made three interlocking aesthetic claims, together with an explanation of each. Now you go to have a look at the painting. You are bowled over by it, and you decide, rightly, that my aesthetic pronouncements are false, and that my explanations of them are absurd. Haven't my claims been falsified just as much as my nonaesthetic claim would have been had I said that painting is very small, about 3 × 3 cms., and you, having had a look at the painting, reported that in fact it is very large? Size can be an aesthetic property, by the way, but for the most part it is entirely non-aestheticl. Little wildflowers can be charming because of their size, e.g. wild lupins. Some houses are attractive partly because of their size.
Most aestheticians make the distinction between aesthetics and philosophy of art, with "aesthetics" being the wider term and "philosophy of art" the narrower one. "Philosophy of art" is only the philosophy of works of art or art objects as they are unappealingly called these days. In other words, these philosophers accept that it is not only works of art to which the terms of aesthetic appraisal apply, such as "attractive", "unattractive", "lovely", not lovely", "unlovely", "majestic", "grubby", "oily", and on and on, without end. They also apply to the human face and the human form, to nature and parts of nature, including natural landscapes, the sea, etc. There is practically no word, I believe, that cannot one way or another be used as a term of aesthetic appraisal. The aesthetic is everywhere; a happy thought.
In general, the fact that everyone agrees on something is not really enough to make it true. The fact that everyone believes that Brazil is the best team in the World Cup doesn't mean they will win the Cup, or be the best team.
On the other hand, if I believe that Jennifer is my best girl, then she is my best girl. If we all thought that blue was the best colour, then it would be: "our best colour", so perhaps it could be said to be the best colour.
So I think "the best" is used in two ways in your excellent question. (1) It just means "the best" by some external standard, goal-scoring perhaps, so that "Brazil is the best team" means that Brazil will win the Cup. (2) It means that blue is our best colour, the best colour of all of us, the one we all like the most, then it is the best colour - of all of us - though not in the first sense.
I think perhaps it is a little difficult to know how to understand what the fact of being the best colour is. There is something good about each of the colours, no? And also, what are the tests of excellence in a colour? What makes a colour good, better, the best? If it's brightness, then black is a bad colour, and white is a good one. If it's richness, then purple is pretty good, and glossy black. Grey is a bit dull, but some people find it muted and elegant. A sparkling yellow sun on a spring morning has a great colour. So we need to decide what the criteria or standards are here. That might be hard. Or there might be lots of different ones. The best butter knife is not necessarily the best weapon.