It all depends on the situation. They all taste good so the decision comes down to choices about your hunger vs the general well being of the subject body of water. I have several ponds and BG form the basis of the food chain in them, hence I never, ever kill a BG. The predators in the pond take care of them just fine.

In public places, if everyone would impose a slot limit on BG, i.e. releasing all fish above 7 or 8 inches, we would all enjoy better quality fishing.