Which of the following language(s) should become the official language(s) of Humanity?

Spanish. It's the language of poorer people and would give them an advantage, and it has vocabulary and grammar in common with Portuguese, French, English, Italian and other languages, making it easier to learn. It's also less imperialist than English. Chinese is an easy language but the number of people who can speak it other than the Han is too small for it to be truly international. One solution might be to *speak* Spanish but write it in hanzi.

There should never be just one official language of all humanity. And all three of the ones you suggest are already official languages somewhere in the world [but not in the United States, which has no official language].

None of the above!!!

The following for humanity:
Kindness, caring, benevolence and honor.

It's difficult to learn these things today.

What do you mean by 'should'?
And how do you imagine you could enforce it anyway?

Humanity should never have official languages. There is no way to currently enforce that anyway, since there are many different nations, none of which have authority over the others.

Even the United Nations does not represent all have humanity, nor does it have the authority to impose its official languages on everyone else.

None of those should be treated as "more equal than the other languages"

There are almost 7000 languages in existence and all the ethnic ones deserve to be kept.
If you want everybody to be able to talk with everybody, you need to choose a non-ethnic one as "the" world-language, one that's easier to learn than any of the ethnic ones.

Until something even better comes along, I support Esperanto for that role. Esperanto can be learned in a few hundred hours, while Mandarin or English requires thousands

The six official languages of the United Nations are Modern Standard Arabic AND Mandarin Chinese AND British English AND French AND Russian AND Spanish.

Pray to GOD on this.
So far Spanish is the most common socially.  English is the most common for business. 

As I don't speak Chinese or Spanish, I'd hope that it would be English.

Language of humanity cannot be binded among languages in such way.

English first, then Spanish.

English what other language is there?!