I just reviewed several of my lists, and have the following assessment in hindsight:
1. List of 4 - actually a very good basis to do a one-semester course World Humanities Tutorial. For deep reading, and also introduce each genre, tradition, context and impact around the 4 key texts. Possibly adding Shakespeare to over-represent the currently dominant western-tradition, and the predominance of literature in humanities and canonical texts.
2. List of 12 - Interesting one-semester course, can introduce works chronologically, and with each work either introduce the genre (3 intros: History, Literature, reiligious/philosophical), compare with the other work in the same genre (3 comparisons: Sima Qian with Herodotus, Bible wiht Samyutta Nikaya, Wenxuan with Mahabharata), summarize regional tradition read (and what happens afterwards; 4 regions), and gives some historical context for "gaps" in intellectual history (esp. Near East prior to Qu'ran; European Middle East). Lack of Plato / Aristotle / Augustine will be a turn-off for some students.
3. List of 25 - somehow I continue to dislike this list. Somehow without classical Literature, Vedic texts, and with only Bible and Augustine to represent Christianity - all these I can't accept with good conscience. Instead for a 2-semester course, I would pick instead
4. List of 16 - There is something nice, clean and symmetrical to this list. Neglecting more intricate "balance" consideration, adding another 4 texts to represent the later Western tradition might just be the thing to cap it off as a 20-text 2-semester course. Which four texts? Something like Dante, Shakespeare, Gibbon and Kant.
5. List of 50 - This list is a good base for a 4-semester (2-year long) course - can even be an AP exam done at high school level if so wished. The sub-tradition split is a bit two fine, but can be recombined to a) 12 texts for South Asian and Buddhist; b) 14 texts for Greco-Roman and East Asian; c) 12 texts for CWANA / Islamic; and d) 14 texts for Christian and European. This would be somewhat modular, and can be covered within each of these 4 courses in a chronological manner, with the exception of doing Greco-Roman separate from other East Asian texts. The chronological element will be challenging - as Christian / European needs to be covered last, but that would leave CWANA / Islamic discussed with students before the Bible (Old and New Testament) are introduced. Maybe there are other ways to cover these 50 texts in some modular and logical order that would be easier for students and instructors alike.
6. List of 36 - could be made to cover in 3 semesters - by breaking up the Buddhist one with the 3 Chinese works going into East Asian, and the other 2 South Asian Buddhist texts going to South Asia. There is a choice here - one way is to do chronologically and combine South Asian with Greco-Roman (both started politically kind of as "flanks" and successor states to the Achaemenids - and it is the political development that makes what happened before then canonical), while talk about the Christian-Islamic-European as one later sequence. The other way is to do simple East-South-West division, in this case Islamic will be lumped with South Asian, and Greco-Roman - Christian - European will form a progression. Whie it can be done this way, I do feel the "Analysis of the List" is right in that there are some important weak points to this list.