Inferiority and superiority depend on the value of the axioms underlying them. A good axiom, one that will lead to a superior philosophy, is one that is so obvious people stare at you as if to say, "Well, of course that's true, why would you even mention it." When you get axioms not rooted in cultures, you're getting somewhere.
Can you get to one philosophy that is superior to all others? It will have to be pretty generic. The only axiom I can think of is it must be based on liberty.
Define "superior". Personally, I'm an outcomes-based kind of guy - a superior philosophy is one that produces an improvement in the human condition, and an inferior philosophy is one that leads to a worsening of the human condition. But that, of course, depends in turn upon how I define "improvement" and "worsening", not to mention "human condition", so we'll have to argue about that and form some consensus there, too. And naturally, I'm abandoning claims of universal truth in favor of purely pragmatic considerations, but there's an up-side to that - once we agree on the desired outcome, it's a hell of a lot easier to show that something's useful, versus showing that it's true ;)
How about one that has demonstrated its robustness over several hundred million years -- Survival of the Fittest? Or its companion, Might Makes Right? (After all, we can see that the strongest tend to be the fittest.)
True, these ideas are not particularly kind to the idea of liberty, but they do seem to meet the evidentiary standards that Rand would demand of an objective philosophy.