Most highly regarded. So that is about having the reputation of being the best right? I have not tried enough of them to answer which is actually best, but if you comb through the forum and have to find some kind of consensus, then I think you would find that Filco is the brand often mentioned when people are talking about a quality MX board. That is not to say that other brands like Leopold and so on are thought of as bad, but it seems that at least in the minds of people Filco is the benchmark.
Of course, that does not mean that everyone would agree with it. While a non-issue for most, some people would rather get a board that does not have the infamous ping. Or a board with other stabilizers. Or a board which comes with PBT stock keycaps instead of Filcos crappy padprinted ABS ones, and so on. But, we are talking overall reputation here.