I highly think that question of type "What is the best..." bring a lots of useful information to people. Perhaps it should not be accepted in Stack Overflow, I agree.
But I would really appreciate to have access to a site where I could ask those kind of questions. Ideally, the site will have a similar well tuned awards system as Stack Overflow. Also it would be nice if that site would have a very nice popularity as Stack Overflow. For each user on that site, just beside its reputation could be displayed the reputation from Stack Overflow (without being able to affect it) if it exists, that way it could help to evaluate the quality of an answer.
To add some considerations (explanations) to my suggestion, I invite you to read one of my really not popular question at meta.stackoverflow.com: Questions of Type: "What is the best..."
Sorry I just discover http://area51.stackexchange.com/ as Emrakul told me. You can close this, I can't ! In "Contact us" they do not mention how to send suggestions.
If anybody can close that, I would appreciate. Sorry to disturb !
FYI: Please take a look the fourth in the most voted questions on StackOverflow (not subjective ???) !!! And I would be surprise to see all others that are deleted :-) !