Aesthetics is a philosophy branch. I like this question (topic).
Well, let me see...Hmmm, I think the left one (the first one) is more pretty, in my opinion.
And yes, the aesthetics' standards are very different, they depends of the time (for example 400 years ago in some place people prefer fat women, but now, in the same place, 400 years later, they prefer slim women), of the fashion, of the individual, etc. Also it's not only about the people (faces, bodies, etc.) It's about everything. For instance - the colors. Someone likes green, another one - red,...and so on.