If we want to argue that no pigs have wings, it would be fatuous to focus on just one pig: that wouldn't prove anything. But if someone wanted to disprove the proposition, one winged pig would be sufficient.
While that is true, arguments about the best evidence against evolution need not rise to the level of proof, they might just point to situations where the evolution explanation seems the most troublesome or questionable.
For example, if I were to be asked about the best evidence that general relativity was not correct, I'd probably point to the need to point to dark matter to explain things that are not beyond the realm in which Newtonian gravity should apply. Of course that would not be proof, just an argument. I might next talk about dark energy and then about whatever my pet theory was regarding red shift quantization.
I would not then have one killer piece of evidence, just a bunch of stuff about which I was highly suspicious.
Similarly, there might well be questions for which evolution proponents have answers, but for which the answers are speculative or weak. It might well take a large number of such arguments to constitute a substantial argument against evolution.
Now admittedly, the last person to react to the one best argument question spouted a bunch of Bible verses and PRATTs, but maybe someone else could do better.
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King
If there are no stupid questions, then what kind of questions do stupid people ask? Do they get smart just in time to ask questions? Scott Adams