The problem with a “best settings” utility is that the best settings for your hardware is highly subjective. Some people are only concerned with high FPS/low stutters, where others have a higher tolerance for lower FPS and want maximum eye candy. And of course there is all kinds of variance between the two extremes.
With a tool like that most people would probably end up having to tweak to get to their own sweet spot, and would end up having to figure out what each of the settings are for anyway. That’s why I personally doubt such a tool would be much more useful than the default performance profiles that we have today.
Here are some threads that I have found extremely helpful in figuring out what each setting does and what its impact might be:
Note that in the second thread referenced above the OP removed most of his original post for some reason, however if you scroll to the last few posts, someone has reposted it.