One of the reasons that we delete questions at math.stackexchange is because the answer is primarily opinion based. However, my observation is that there are still many such questions; they are not only never closed; instead, they are usually highly rated.
Here are a list of few examples:
- List of interesting math podcasts? (Interestingly, the question List of Interesting Math Blogs is closed though I failed to notice any substantial difference between the two.)
- What is your favorite online graphing tool? (Is not the answer to one's favourite questions "opinion based"?)
- Where to go after calculus?
- Your favourite maths puzzles
- Good books and lecture notes about category theory.
- List of interesting math videos / documentaries
- Math Major: How to read textbooks in better style or method ? And how to select best books?
I believe that there are much more such examples that are difficult for me to exhaust. My question is: do we allow such questions, or should we close all of them (or some of them) as they are opinion based?