Depends on how fast you want them to thaw.
Seriously though, I try to only let them set on the counter as long as the outside temp is around 36-38 degrees, once they start to go over that, then in the fridge they go. Think of it like this, if you plan on cooking them right away, you can do all sorts of things to "speed thaw" them such as the bucket of water method mentioned above, it does work quite well. But, if you plan on thawing them today and grinding them tomorrow, it would probably be a good idea to take a slightly slower approach.