I think Philosophers stone is better.
Perhaps because I'm in england and that's the title here. Also that is the original title.
Also the philosophers stone is mythical and goes beyond and further back than the Harry Potter books. I'm not entirely sure where it first originated but the earliest mention I have heard of it was in Hans Christian Andersen's 'The Philosopher's stone', written in 1859. I think it goes further back than that, even. The exact nature of the stone has changed throughout different reincarnations in different stories, though stayed fundamentally the same. This is undoubtedly where JKR got her inspiration.
I'm a big fan of Hans Christian Andersen