Rule 15. A good steak is best served medium, not well done.

This is all about preference. But if you are supremely sketched out by the establishment that you are dining in, by all means get it cooked well done. On the flipside, if this is a swanky place,  you can dance on the wildside going medium rare or even rare. But my personal preference is medium, you get just enough juice without the upset stomach possibly later.