Yes, best is unfortunately considered a naughty word because it is a single word that turns any question into an opinion question. It suggests that there is only one solution worth considering, and people may be less likely to post multiple valid solutions in a single answer. It essentially asks, "What is your favorite ____?"
I actually have the opposite opinion from you and think there have been many questions which should have been put on hold for clarification, but instead many people answered them. If I can catch them before there are very many answers, I usually do put them on hold, but sometimes an answer has some insight into the question that I missed. Other times, I have to pick my battles. If there are already several answers from high-rep members on a somewhat vague question, I realize I would be fighting an uphill battle and I should probably save my time and energy for something else.
I was actually disappointed when the "best surface" question was put on hold because I was in the process of writing an answer, but I didn't have time to argue the question's merits at the time and at the very least it would have been nice to know the relative budget of the project.
An easy way to change a "What is the best ____?" question into an objective question is to ask instead, "Is there a best ____, and if so, what is it?
Another way to reframe these questions in many cases is to instead ask, "How would I determine the best ____?"
However, as Matt pointed out, "best" in the question title can be acceptable as long as you can adequately clarify your criteria in the question body.