One crucial difference between people's preferences on the matter, seem to be how we interpret a citation. Is it a word or is it a mark/reference? A word should be part of the sentence. A mark/reference may mark the sentence itself and should therefore not be a part of it. A citation has the purpose of referring to further reading elsewhere, and therefore sends you off to some other text. The citation is not a word, in my opinion, unless it is a subject or object as part of the sentence. In options 5-7 the citation is an object, while in options 1-4 it is not a subject/object, but a reference marking the sentence or the last word. Citation may be treated or read as a word in some formats, like APA, but not in formats where the citation is just an index in the bibliography. Footnotes are common behind punctuation (without white space), and I think references should be treated similarly. (Some formats even use superscript for citation, just like footnotes are marked.)
Option 4, 7 and 11 (without whitespace after punctuation) are preferably. Here's my reasoning: What is intuitive and what can cause confusion?
When citing/refering to a word or expression or person in a sentence, it makes sense to refer to it immediately after. with a list of different words to cite, it is easier for the reader to follow which citation refers to which word. Citing a person would look like options 6 and 7. Choosing between them would be a matter of aesthetics. Maybe option 11 is a good choice (but without the white space after full stop), as a citation mid sentence tends to make the sentence harder to read.
To quote user1101674 in a comment on this thread:
As mentioned, they [options 1 and 11] allow for the distinction between backing the
entire sentence, or just a specific part of it. So if they were
commonly understood in this way (apparently they are not), they would
indeed reduce ambiguity.
Using the citation as a word in a sentence looks a bit untidy. Specially if you are going for the citation format of superscript number: According to ^1, more coffee is always better. (This is option 5.)
When paraphrasing a statement (like options 1-4) it makes sense to put the citation behind the punctuation (i.e. option 1 and 4, but I would choose option 4 because it connects the citation even tighter to the sentence). This is intuitive for three reasons. First of all: You first make a statement, which should end with punctuation. Then you cite it. In my view the citation is not a word. You don't read it out loud. The citation is not part of the sentence, but refers to where the reader can read more about the sentence.
Secondly it is less confusing and more consequent and neat if there is no difference between citation location for quotes "bla bla."[XY] and paraphrases: bla bla.[XY]
And don't forget if you are quoting a sentence with citation: "bla bla.[AB]"[XY]
Thirdly it would be very confusing if readers cannot distinguish a paraphrased sentence from a referred word. If the last word in a sentence is a referred word, it would look like option 2 or 3. How can you tell it apart from the case where option 2 or 3 are paraphased sentences? Does your citation regard the word "better" or the sentence "More coffee is always better."? Therefore option 2 and 3 show confusing citation sites for paraphrased sentences. We are left with option 1 and 4.
Choosing between option 1 and 4 is for me a matter of aesthetics, so I opt for option 4. Maybe someone can come up with a case where it is natural to have citation first in the sentence? If so, there may be a semantic reason for option 4 as well.
Language exists in order to understand and be understood. Therefore language and grammar ought to be designed so that confusions are avoided. That's the purpose of language.