The best pics uploaded on Facebook to date, is a very hard question to answer because it is asking for an opinion. An opinion is a belief or judgment, so what I may think is “best” may be completely different from what you think is best.
For example, I love pictures of outer space, nature and animals. You may like architecture, abstract photographs, or things like automobiles, bicycles, furniture, and so on. In addition, some of the best pics on Facebook may be private and you would never even be able to see them!